You guys should add a rank system, for example: Recruit, officer, corporal. The better the rank, the better the gear and weapons. Also maybe more exciting call outs as your rank up. I am just scratching the surface with what could be done with ranks, get creative!

This is something which has been suggested and discussed multiple times, and I don't think the Development Team has any plans over ever making such a feature. This is mainly due to the fact, not all people want a ranking system when playing the Modification, they just want to get in the game and play in a less-realistic, more arcade like mode. On-top of that, most callouts are plugins developed by members of the Community, so a ranking modification, would mean that the Development Team would have to write some sort of sophisticated code to have callouts for different ranks.

This is all quite a lot of work, for a feature which is not guaranteed to be used much, however I believe I saw something in the gallery recent which is a modification which I gather will be somewhat like you have requested. You'll have to keep your eyes out for that.