Generally, I find players who flock to the "low amount of shots to kill someone games," tend to do so for the easy kills and lack of skills. Basically, they like it this way, because they don't have the skill to last in a prolonged firefight. This is just what I have come to notice - A player that rocks in MW2, will generally get destroyed in a game like UT or Quake 3 or even ET or QW.
MW relies on reflexes and flanking.
Halo and Team Fortress tend to rely on consistency. Both Halo and TF2 usually provide large spaces rather than corridors, and corridors tend to be in buildings rather than between them, often with at most three very linear choices. On top of that, until Reach, Halo never had a mechanic to catch up with enemies, Team Fortress will likely always lack a sprint button, seeing as valve only distinguishes between running and walking.
Hitting someone in the head realistically does more damage, but in a game it is about being a perfectionist. With fast moving targets it is hard enough to trace a body with lag, far harder to trace a head. When the majority of players have fast internet connection, then we can focus on precision, but until then, you are still going to have the people who aim at the head and miss with instantaneous bullets.
Any game could take out camping in a 3 shot game, but no one has actually felt like innovating heart rate (where high heart rates are good for CQC). Or something else, that's how I've always looked at it.
Reflex fighting tends to be faster paced because it often involves two people fighting for very short instances, implying more running, a simple shootout ends up being a mind game, "if he is running this way, how do I cut him off and shoot him in the back?" A lot of people who have precision tend to be unable to navigate winding corridors so that 1) they do not get shot in the back, 2) they avoid facing larger groups head on, and 3) they shoot as many players in the back as possible, even if the enemy is in large numbers. It may be "cowardly" but you have to call it skill.
In high health games, sticking together is more prominent because those crucial few shots to the back won't kill both players before they turn around, at best one player will die and it will still end up being a fair fight between the remaining two (unless both players are oblivious to damage, death, and loud noises). Another problem is that during extended fights, players tend to profiteer and interfere with what would have been a one-sided fight. Eventually a small 1v1 fight may become a 6v6 fighting instance. In a head on 2v1 battle, 2 will usually win the 1, the only thing that can turn the tide is the grenade, skill, better weapons, or blind luck.
MW2 failed because of longer range shotguns, One Man Army/scavenger for noob tubes, OP killstreaks, the ability to build killstreaks with other killstreaks, and ironically nerfing prep-able grenades. All of these promote and reward camping. In CoD4, it was rare to find the lone RPD camper in any game, in MW2, they will camp with anything they can get their hands on.
» Fri May 27, 2011 3:12 pm 
Second of all - the character creation. If the game would be grounded in realism we wouldn't have all sorts of cool items. They would just be very bland and they would need to serve a purpose. But with cartoonish style we can make all sorts of cool character which wouldn't fit in the game otherwise. And look at the Heavy guys. This is similiar to TF2. In TF2 they made all characters very different so you could easily tell what class they are just from their silhouette from far away. Same goes for Brink. The heavy body type does not look realistic. But if it would it would be hard to tell from far away. It is as simple as that. 
) but I also like more realistic ones like BC2 and COD4. (For some reason I no longer enjoy playing TF2) 
