there is a very simple reason why call of duty 4 was the best.
it had 3 kill streaks
uav, air strike, helicopter
that was it everyone had the same and there was no point to camp for it cause you could easily run around and get 7 kills so everyone did it
flash forward to now and they have the MOAB at 25 kill streaks....people want all the fancy stuff so they sit in corners trying to stack kill streaks, that is what Infinity ward did to call of duty they wrecked their own game.
Honestly if they would have kept the same kill streaks or went no higher than 9 the game would not have turned into the gay camp fest it is now.