Can't comment on DayZ as I haven't experienced it but if you're saying that it could help, it may be true.
I still want shooter that would require precise calculations for shooting and aiming xD
I haven't played them myself, but I'd still venture to say that the
Sniper: Ghost Warrior games are the best we're getting in that department for now. There, bullet trajectories are subject to wind, gravity, and flight time. There's more to it, but it's a lot better than the old Resident Evils where you held your gun over the dog.. and still hit the dog.
I want to agree that you can sort of learn about shooting a real gun by playing a shooter, as I had played plenty before I fired for the first time I'm inclined to believe the prior knowledge helped a bit. But I'm not really sure, the whole thing just came natural.
I think besides the things that have already been mentioned, games can also teach values and dive into moral and philosophical problems and decisions. Take for example games that let you be either good or bad. Depending on your choices, people around you react differently, like they would in a real world scenario. The player can pick a side, but he also has to live with the consequences.
I have to say.. games with moral choices taught me nothing. xD
I've always chosen my paths based on what was best for my character and I always assumed everyone else did that, too. My big question always was,
"Which option will land me with the better gear?"
For example, Fallout 3 and NV. In Fallout 3 I was evil because it was most beneficial to my character, whereas in New Vegas I was usually a saint (save for achievement-required run of the Legion story) because it was most beneficial.
I'm not knocking your response, just saying that there's plenty of us out there who didn't care about the morality of the situation and didn't take anything home from it. My feelings have always been: It's a game, just shoot the guy, take his stuff, and leave.