The only games I still play are all turn-based and two-dimensional. Realistic adventures are not fun. Just like real warfare, they consist of long periods of boredom followed by short bouts of terror.
However, you have to have realism when you want a player to be able to intuit the next move. If your puzzle isn't based on physics, then you have to spell out every option for the player -- not a problem, as long as you take the time to do it.
The second use for unnecessary realism is creating an emotional reaction. Humans are wired to react to real humans with hair and jiggling and all. If you don't see that in the game, your player's back-brain is thinking, "mannequin!", the whole time. You can still have emotional reactions to simple games, of course, but it's arguably stronger to a realistic character.
The worst drawback to realism (apart from computer requirements) is that any flaw becomes that much more obvious. Even state of the art games tend to suffer from this.