The funny thing is, I’d disagree on TPS. I don’t think TPS needed DLC Vault Hunters, what it needed was more campaign content. TPS was already a smaller game than BL2’s base game, and rather than the DLC trying to expand TPS into a more sizable experience, instead it had 2 new characters which just made you replay what was already there. But I guess making 2 new VHs was easier to do than making 2 more campaign DLCs.
I think you are right, BL3 doesn’t need a massive roster. But I do think that if the game is say, 1.5x the size of BL2, or perhaps even twice the size of BL2, it can justify adding in 4 new VHs as well as the season pass of campaign DLCs.