I had kind of hoped we would have gotten a post-Epilogue trip into either Mexico or further out west than New Austin for John or Sadie or Charles with some new missions, Strangers, trinkets and talismans, Legendary Animals as a single player DLC. Get Charles from Beecher's Hope to the Canadian border or Sadie through Mexico to Brazil kind of a thing.
And like you, I would have paid full price for both of those or a Undead Nightmare DLC. I liked RDRO for what it was, but it was just limited, almost like the development team just didn't know what to do with it beyond "shoot your online friends in the Old West".
Despite all of that, RDR2 is my favorite game of all time. I know a lot of people thought it was overrated or a hack job or whatever, but I thought it was an amazing story that I've had to replay a few times now and each time I get something new out of it.
It's funny but GTA:VC was my favorite from the day it came out, mostly because it was like letting me live Miami Vice, and while RDR1 really was amazing, it just couldn't quite nudge it Vice City out of the top spot, but RDR2 did.
Now if Vice City had the sheer scope and options San Andreas had, it might be a different story. Some parallel universe has that version of Vice City and I'm jealous of them.