There are certain areas where I feel the artist's vision has to step back -chief among them promotion of bigotry and disability accommodation- but in other areas, I still see merit in the "artist's vision".
Sometimes it's simply true that people want a game to be something other than what that game was designed to be, and in that case vision becomes a legitimate argument. Too often, people conflate things they wish the game had with things the game is weaker for not having. Exclusion, in certain respects, is a legitimate design decision; many of the arguments I've seen against the idea of the artist's vision deny this outright and that's where the "vision is pointless" argument hits a wall for me.
Even if the artist themselves didn't have a cohesive "vision", the game itself still does and a game isn't any weaker for refusing (to an extent) to diverge from its vision. That vision can still be critiqued, but "Because the artist wanted it to be that way, this work of art just isn't for you" is still a valid answer to most critiques of artistic vision, and a game doesn't have to justify why it is a certain way just because it should be expected to cater to more people. However, again, I believe accessibility and avoiding bigotry transcends this argument.
edit: Hell, if the vision wasn't important, there'd be nothing to criticize in a game or talk about. The vision is the essence of the game, and even if changes a lot, I don't see how it could be called "worthless" by any metric. Is the vision successful or not? How could it be better conveyed through the detailed aspects of the game? These are the exact questions that all game criticism revolves around.
