Personally I think them not having much to do on the planets besides the first hubworld did more damage to the game IMO. The one guy I knew who played it extensively essentially got fed up with the big sacks of nothing after that and considers it one of his most hated games.
I'd say more than that Outer Worlds just isn't anything.
It's not Fallout because it lacks charm (or the rare occasion the writing is good). It doesn't leverage it's setting into anything interesting (aka Star Wars, Star Trek, Mass Effect, etc) and the gameplay is very basic.
It feels like a video game that was made for a Movie that didn't want to license a real video game.
Lack of content is a valid complaint, as is the game not really having an identity except for "Fallout but in Space". You can't really defend the game for not knowing what it is when it has such a confusing tone thru out it, not knowing if it wants to be a parody or a grimdark post-apocalyptic world, but you can definitely blame the marketing department for not making it clear what the game was going to be. I avoided all marketing for the game, but my understanding was that people knew two things before launch: 1) It will be like New Vegas, which sets up all sorts of expectations, and 2) It's got a lot of humor and won't take itself seriously...so why a story about a society, not unlike ours, that is falling apart? Won't that hit too close to home and will need some really good writing to make it land? How are we supposed to get immersed into it when every other dialogue has a redditor trying to crack a joke or advertise something to us? Inspirations from KOTOR and Mass Effect are obvious, but not nearly prominent enough either, at the end of the day it's obvious that the game is a spiritual successor to Fallout and it was marketed as such. No wonder people were disappointed when they got something completely different. No Mass Effect fan was disappointed by Outer Worlds because they didn't even know it was trying to pander to them.
Another thing is the lack of content the game has. This was by design, Tim said he wanted to make a smaller scale game, similar to the first Fallout(which you can complete over the weekend) rather than a massive RPG you think of nowdays, especially from Obsidian. People tend to forget that Fallout also started out rather humbly, it wasn't until Fallout 2 when the franchise became this massive, lumbering game with a giant sandbox and plenty of things to do, with runtime lasting dozens of hours easily if not over a hundred. It makes sense to start small with a new franchise, to ease the players into the world to set up for a much bigger sequel, and you can see that Outer Worlds is designed for just that: small zones, not a lot of quests, the game is constantly going at a breakneck pace, constantly giving you new weapons and armor because it is so short you don't have time to really think about min-maxing your gear stats, locations come and go but there is a few times you can optionally return to them if you want to(just like in Fallout 1, which was a very straight forward journey where you usually never went back to a location once you completed all the quests within it). I don't actually have a problem with how the game is designed, I enjoy it precisely because it has so few strings attached to it, I can complete it over a course of the week happily vs a playthru of a Fallout, Elder Scrolls or other big cRPG that will easily take me weeks, if not over a month to complete.
So, where does the problem actually lie? We go back to the marketing, where the game is happily telling you that it came from the makers of Fallout: New Vegas. The game has an open world with plenty of side quests to do...but they fall short of what New Vegas offers due to the small scope of the game, something that wasn't advertised. The game has many factions and faction reputation system...but it is so short, it barely matters, unlike New Vegas where having a bad reputation with a powerful faction early on would fuck you over with hit squads and failed quests up the ass. Outer Worlds also has a gritty, dark world where choices and consequences from the player shape it every step of the way...but it is not nearly as grounded as the one in New Vegas, has way too many jokes and humor that makes it fall flat, and the game is over before it really even sets the stakes, meanwhile you always know just how close to the final battle you really are in New Vegas thanks to the interactivity from the game world and the constant urgency major quest givers give you relating to it. Really, the only promise that didn't fall thru was being able to kill everyone and still finish the game, not many games do that these days.
So, as you can see, the game marketing didn't exactly lie, it simply gave off wrong impressions because telling players this is a small game that can't hold a candle to the one they made before, the one referenced in every piece of marketing material, isn't a good idea. What didn't help matters was that Outer Worlds came out shortly after the disaster that was Fallout 76, a game that was so bad it became a laughingstock in the entire industry overnight and even turned a lot of Bethesda dents into Bethesda a-logs. Fallout fans in particular were disgusted at what Todd made of the franchise, and they needed a W real quick. Lo and behold, Obsidian is back and they're making New Vegas 2, they even have Tim Cain at the helm! Fallout is saved, Bethesda will be BTFO even more! You see where I'm going with this, right? Nobody won, because New Vegas 2 never came. People who would never be interested in Outer Worlds only bought it because the internet promised them it would kill Fallout 76 or because it promised them it would be the sequel to New Vegas, neither of which were true. Outer Worlds is a spiritual successor to the ORIGINAL Fallout, and in that sense it does the job rather well, despite the faults some people might have like the writing. Any other Fallout game, and we're suddenly comparing apples and oranges, but it's hard to see it that way when Obsidian marketing really wanted to let everyone know this came from the same devs who gave people the game they really liked, something they did with the marketing of Outer Worlds 2 as well so they haven't learned their lesson.
So, where does that leave us? Outer Worlds is forgotten because the game was falsely advertised as something it was not, and then the people who did play it hated it because it wasn't what they were expecting. Then you have people who never played the game, but still parrot the same false points made up about it from some youtuber or a /v/ post because nobody will correct them, nobody cares to and that's why these pseudo-intellectuals see it as an easy target to prove how smart and based they are or whatever. Taking all that into account, you can't really be surprised the game flopped, but at the same time I don't think it deserved to. Once you look past veil and accept that it is not New Vegas 2, it is a solid bite-sized RPG that tries it's best to repeat the success of Fallout 1 while doing it's own thing. The small scale and short runtime make it very replayable, and the base is solid enough to warrant a sequel, most importantly the game world is established well enough that you want to know what happens next. In that sense, Outer Worlds succeeded, but that requires someone to play it thru to the end and understand the whole debacle behind it, as well as playing Fallout 1 in the past to properly appreciate the game. This leaves a very small niche of players whom this game is truly targeted towards, unfortunately most people who played it were uber casuals who played it once and then forgot about it or scorned Fallout New Vegas players who were upset they didn't get a sequel, much like how
@Adamska described someone who expected a heap of content and a giant open world and got neither of those things. Original Fallout didn't have either of these things either, and frankly I knew the game wasn't to have them since I knew Tim was making a Fallout 1 styled title, but how is your average modern RPG tourist that can't tell one RPG apart from another supposed to know that? They shouldn't need to, Obsidian should have been much more clear on how the game was going to be designed, and the failure to do so is on them.
I haven't played the sequel yet, maybe it elevates the franchise to the next level, maybe not. Either way, ironically enough what the franchise will be known for the most going forward will be this massive confusion the marketing made(as if Outer Wilds confusing people about the two games due to similar titles around that time wasn't enough) and the fallout behind it, resulting in waves of New Vegas fan a-logs who now despise the brand for lying to them. At least it's a funnier backstory than what Avowed got, which is just being a shitty, woke Pillars of Eternity sidegame absolutely nobody cared about and nobody remembers now. The funniest thing about that game that happened was PatricianTV having a meltdown because people called it "woke" and the fencepost he has stuck up his ass started hurting upon hearing it, so he naturally had to make fun of both sides to feel smart and intellectual again. Nobody actually remembers the game or anything about, even Outer Worlds has "so stupid it hurts" scenes people bring up like the various bad bits of dialogue, Avowed just has nothing.