I really like the idea this game is talking about implementing. Realism would be my main reason for buying it. Since we all like different weapons how about releasing weapon packages. Say have one with the AR/M16 family, one for HK, One or AK varients etc. The same would go for pistols and smg's. That way people could download whatever "weapon package" they wanted to use so they didnt have to sort through a whole list to get to the ones they use. You could even add in a preferance list outside the game to work like a mod where they could further delete cetrain weapon from appearing as options in the loadout screens.
On a side note ive always thought the High Standard OSS pistol is cool and would like to have it in the game. Delta force i think was the last game to have it.
I have always liked the ability to pick up an enemys weapon and search their body for ammo etc. On allot of games it isnt practical to carry a sniper rifle the whole time but if you kill a sniper you could use their weapon for a while then drop it for another.
Suppressors would be a great addition i think. Not only are they a great flashhider but the noise reduction is good too. Its function would be to make it harder to pinpoint your position and at long ranges your position would be almost completly hidden. The only reason damage or range would be less with a suppressor is if you use subsonic or otherwise underloaded ammunition. So unless you plan on adding different ammo types dont reduce the damage or range a suppressed weapon has. A suppressor will in many cases add velocity, reduce recoil and be more accurate. I have a suppressor and it takes all of literally 5 seconds to screw on so much more than that would be unrealistic in my opinion.
Bipods and customising the optics would be great. Having the option between a Acogs, Aimpoints, various scopes would be very good. Say if you choose acog what reticle would it have or would there be multiple options? We all have diferent playing styles so giving us the option to cater to that would really add to the game. Including that reticle issue.