I 100% agree with Amir0x... with two exceptions.
The first is where you've been led to believe though marketing that the game is something that it's not. That might not be relevant in the long run as people will come to understand what the game is supposed to be but at launch it's certainly relevant. For example, criticising Brutal Legend for what it wasn't (a decent action game) was in fact a legit criticism considering they sold the game as something it wasn't. That shouldn't have been the entirety of the criticism but it was, I believe, a valid point.
The second exception is games within franchises. While people should be free to innovate within a franchise, mindless change from a formula people expect can be criticised if it's not justified by the game design. That should only be a small part of the criticism, but I feel like it should be allowed. A good example here is the battle mode in MK8. We all know what a good battle mode looks like because of past Mario Karts. MK8 didn't had something different, but worse, and for no apparent reason. That's fair game, imo.
BUT - Here's the opposite point to OP's, and it's the SINGLE THING that annoys me most about talking with games with people -
If a game DOES attempt something, then that thing IS a target of criticism if it isn't achieved. So if a game spends a third of it's run-time in cutscenes telling a story, and that story is absolutely shit, then you don't get to say "Who plays games for the story?" No. 33% of the time, you had a shit experience. The devs tried to pull something off and didn't manage it, and it hurts the game. You can't handwave that by appealing to the fact that games are supposed to be an interactive medium or whatever.
The same can be said of games that have bad minigames or extended poor level design at parts - you can't handwave that stuff just because the main gameplay experience is good, everything must be seen as part of the whole.
But you also must look at it in context. Mario has a 'story', but it's quite clearly tongue in cheek, and takes less than 20 seconds to set up. It's just a whimsical context for the action, and should be judged as such. Context is everything. But in a game that has a major narrative focus, if that focus is bad then that's a huge minus for me.