Just like movies, videogames are an escape. We want them to be "real" in the sense that we want to suspend disbelief (and thus the drive to create more realistic looking games). But once things look real enough, I think people tend to want the gameplay to be a bit more on the fantastic side. There's certainly room for things like Splinter Cell where you have some decent realism. Sometimes you might want Clancy-style realism. However, a lot of gamers prefer the "Jerry Bruckheimer" brand of "realism".
A personal example:
When I was a kid, I loved playing the original Amiga version of F-16 Falcon. It was a really fun sim and not too difficult to pick up and have a good time. It wasn't ultra-realistic, but it was just realistic enough to make you feel as though you were flying an airplane. Fast forward a few years and they released a sequel (this time for PC with 3D accelerated graphics). They had decided to make a very accurate F-16 simulator. I was so excited to try it out (being a big fkight sim fan). Finally, I would have a realistic military sim with great graphics!
It was so accurate, I found that all the fun was gone. The manual was a huge beast (a three ring binder if I remember correctly) that had all the details of how to operate the plane. I was just barely able to fly the thing. Landing? Forget it. I would crash over and over again. I've logged a lot of hours in MS Flight Simulator and other sims, so I'm sure that if I had practiced and read all the material I could have gotten better at it. That, however, sounds suspiciously like work. I realized that this was not really a game anymore. Furthermore, I realized that the truth is: I don't actually want to know how to fly a real F16. I just want to prentend I'm flying one so I can enjoy raids and dogfight. I want it to be just complex enough that I get a taste of the realism, but I don't want to have to sit there with a clipboard and go through a pre-flight checklist every time I want to take to the air.