It's simple. Baldurs Gate 3 is a game with good gameplay, it expanded over the previous entries, it has freedom of choice for builds and story (In an RPG, a novel concept, I know), a decent story and is replayable.
While Dragon Age: Veilguard has generic action based gameplay, it removed features (like the ability to customice the companion builds in depth), your choice for roleplaying is restricted with various flavours of "yes" (Fallout 4 style), the story is mediocre (At least from what I have read from the more knowledgeable posters here) and nobody likes politics being blatantly shoved down your throat.
Most people don't care about inclusivity or diversity in games. Both for the better and worse. BG3 has a lot of diversity in its cast, but most people didn't complain since the devs had the restraint to not forcefully shove it in your face. With DA: Veilguard you even have leftist complaining how the writting is blatantly trying to pander to current politics. The writters have a fantasy world, with fantasy races, with magic and they couldn't come up with other analogies or ways to explore current worlds issues? They just had to go with shoving the pronouns, gender identity and transgenderism discource in the most bland and uninspired way possible? It's just disrespectful to the audience. Even more so to the fans when they blatantly shit on established canon.
Tldr: Because DA: Veilguard is fundamentally boring in gameplay and story when compared to other or previous games. For an RPG, its freedom of choice for roleplaying is restricitve. Which is antithetical to the genre.