The only realism I care about is the physics around it. While I know that there is literally no way to completely simulate an object moving through space as it should be(Approximation methods have to be used) I still think that games should always go for the best physics, I love halo, but I hate how warthogs and stuff just bounce around like balloons sometimes.
Though that only applies to items that exist in real life, if they put a hovercraft run on anti matter in the game, well, they can make up their own physical properties to it, since no one really knows how to simulate it.