The only thing that promotes camping is the player, not the game. Some players do better hiding behind a rock or in a bush, while others prefer to move about.
I can say this, if you look at a game like HomeFront that had a support like killstreak system, there was still camping. It's just the way some people play.
Going off of your trend:
Halo had people camping by the weapons and powerups
Combat Arms had people camping in glitch spots and other areas not normally accessible
Brink has people camping defending the objective
Camping is just a strategy for gameplay, and if it works for certain players, and they enjoy doing it, they will.
Im just stating how Stackable killstreaks dont promote camping. People think because COD4 only had like 3 killstreaks that people didnt camp. Its just you see more people playing the game. Most people be in a spot and its just coincidence they happen to be right there.
Ex: I go to the back of the map to call in a Gunner. Someone walks by when I come out. Boom i kill them..At the end of the game YOU LITTLE CAMPER!
Ex: Quickscope someone OMG you quickscoping ******. Now you trying to be nice and you Hardscope kill someone. OMG you STOP hardscoping me.
Ex: I get shot by an enemy it could of been the guy coming around the corner or someone else. I know they going to chase me down so im going to kill them when they come around the corner. Come to find out on Theater Mode someone else shot me. So this guy just happen to come around the corner BOOM dead. Wrong place wrong time kiddy...Camper most of the time they probably not. Because someone moves tactical and likes to play smart(Me) dont mean they camp.
Im not saying its not people out there who do sit against a wall. But as long as i been playing no 1 ever really sits somewhere without getting kills. If a guy is sitting in a house and he kills you 3 times. Well its a reason why hes there. Its simply because they are to retarted to stop giving him free kills so of course hes going to take advantage of it. Who wouldnt?
There's lots of reasons players camp, some are new to the game type and like to take it easy, some know that hiding or camping while their first killstreak is up will help them get their next one.
Don't believe me, it happened all the time in MW2, but then the poor map design and plethora of choke points did not help.
Gun on gun, that's why there's a perk that "spots" players hurt by explosive damage, different types of noob tube, still reducing the recoil back to zero and bringing back quickscoping should promote the "gun on gun" gameplay.
Then again, camping is a legit playstyle, if you can't deal with them then maybe the problem is with you, but in this game even if you steer clear of them, they will eventually get their killstreak and then the next and the next.
This is of course all my opinion and as I have not played the game this might not be a true representation..............
I dont have a problem with campers because i check my corners and after a while I can easily spot where the enemy team is just by seeing where my partners die at and where they are located. Im just stating how is it going to be killstreak based when you got the option to be a specialist and run around care free with a streak that dont reset on death.