Agreed. It's not about having a more realistic looking game, but a more realistic game, period. Players should indeed have "vision" and be able to react to what they see, and should be oblivious to what they cannot.
I would love to be able to realistically ascertain whether or not a defender is able to make a play simply by reading his body language, momentum, eyes, etc. If a CB turns his back, he shouldn't know what's going on behind him.
I also think a huge issue with passing is the fact that CPU WR's don't make plays for the ball. Every WR acts as if they're wide-open and never break from their route, even when they're covered. Conversely, every DB acts like the ball is up for grabs, and they actively make a play for it. If WR's had the same ball-in-air catching logic that DB's had, the defense would seem less psychic, and WR's would seem less brain-dead. There might actually be PI calls too.