Regarding the perks, I've come to understand their necessity. They are just another means of balancing the game. In my opinion, this is the most well balanced first-person shooter on the market.
If IW had made the game as realistic as possible, it probably wouldn't have been as fun for newcomers. Plus, it's fun to play with all the combinations of weapons & perks. I used to use the same few perks with each weapon, but now I enjoy trying out the others, even if I'm not as good with them.
My current goal is mastering the iron sights on all weapons (sans sniper & shotgun). The red dot & ACOG sure make the precision shots a lot easier, but I find it's quite challenging and rewarding to pick somebody off at distance with the standard sights and a silencer. Plus it keeps'em guessing as to where you are!
Speaking of, the sights on the M60-E4 have to be the worst I've ever seen! They're so big & clunky, they obscure your target.