1. A game (or a GM) should not force players to act in a specific way. Players make their own decisions. But I expect the stats to determine how successful the actions are. In a good game, stats either don't describe given area of play or have a big effect on it - so you just can't be efficient if your play style contradicts your stats.
2. I believe in honest play. That is: if we agree on what game we want to play, we play this game, instead of trying to abuse and break it (unless we agreed on breaking it, of course). Similarly, we play the characters we created, with the limitations we gave them, instead of trying to circumvent the disadvantages. Games may encourage "good play" (whatever it means in given game) through mechanical rewards and penalties, but trying to force someone to play in a way they don't want to never works.
3. In my experience, bright and charismatic players playing dumb characters work very well. An intelligent player may devise fun ways for their character to do dumb things. A charismatic player will roleplay their character accidentally insulting others or suggesting something entirely different than they wanted to say. When somebody wants to play the character they created, they put all their advantages to work.