Larian worked for more than 1 year AFTER release to improve a game that was already one of the best game ever released
Ha! Larian has indeed quite a lot of work in front of them to make BG3 "one of the best games ever released".
Snarkyness aside, it is a tricky subject. No, I don't think Larian are required to continue working on the game and remake some of its content. At the same time, AAA do tend to launch with "we will fix it later" promise. Now, again, I don't recall Larian ever even hinting for long time support post launch, but than how do you treat 1.0? The quality drop past act1 was very noticable, but it is easy to fall into "ah, they will fixed it later, like they fixed early access area". So when it doesn't happen (apparently, I didn't play the game in a while, so I can't judge it - waiting for final patch for my 2nd playthrough), should one pretend that all is hunky dory?
Well, maybe now when Larian is wrapping support down BG3 evaluations will be a bit more representative of the game.