Considering MW2 leans more towards an Arcade shooter than an actual Realistc warfare game, much like Halo you have people using a sniper rifle and shorter ranges.
I agree it does get irritating watching those idiots running and jumping around like in idiot, much like Halo, but generally they are easy targets.
As for the whole "sniping in mw2 is horrible/unrealistic" you have to realise it leans towards more of an arcade fps, for the bullet drop crap, yeh it could have, but in comparison to bad company 2, the longest shots you will take in mw2, will be the shortest shots you take in bc2, meaning i doubt the overall ranges you would deal with would be affected by bullet drop, if at all, and yeh in mw2 you would be walking around with 15kg rifles and throwing them up and down, in comparison, why does bad company 2 lack sway/breathing?.