The OP makes a good point that not a lot of people seem to get at, and thats the games randomness.
Imbalance, as long as it isn't completely severe, I can handle. MW2, on a general first glance, has enough balance to be playable. Yes, Assault Rifles are king, I recognize that, but at least doing well with an LMG, sniper, or SMG isn't something impossible.
My biggest issue with this game, is its randomness. The game will just out of the blue decide its your turn to die. Its not an added level of depth, its an added level of frustration, to know that you can do nothing while the enemy has you at his mercy. Its not fun to play a game where anything at anytime can happen. Its not exciting, or challenging, its frustrating, for no apparent reason, other than to succumb to the desire that every gaming dev seems to want. More money.
Besides the corner lag, and the fact that often times, getting a kill is purely based off of luck, whether or not your connection decided to bring you up to par or not. And its one of the reasons why dedicated servers would be a blessing on this game. The host system is flat out garbage, infinityward was completely high on meth to even me using this system. Whoever has the fastest connection has a massive advantage, so much so that it can make the game almost unplayable.
Besides that randomness (Which is huge, but at least avoidable if your smart), there are so many other issues where you can die, not because you made a mistake, or the enemy outplayed you, because they got lucky.
A perfect example is the Care package. It is the epitome of randomness. "Drops a random killstreak reward". Its so stupid. It was put in the game for the soul purpose of pleasing the prepubescents, the ones that have all flocked to this game now. Yes, I've heard the "Gives worse players a chance at having fun argument", but honestly, its bullshit. If you aren't mature enough to handle the fact that you suck at the game, and need to get better, your not mature enough to play the game.
The spawns, don't even get me started. The maps, the more and more I play them, aren't as random as I thought. Its the bloody spawns that completely ruin the game. I watch every single kill cam. I want to know what I did wrong, so that I can improve. If I get killed from behind, I expect it to be because the enemy flanked, the enemy took the initiative, and I wasn't vigilant enough to stop him. And then I see the killcam, and realize he spawned right behind me. ******* bullshit if you ask me. Practically ever single killcam I watch starts out with the person who killed me, dying. Thats bullshit.
Its not a matter of being in their spawn either. Their spawn moves, next to you. I have killed large groups of guys, only to have them spawn right behind me, all of them, that created a spawn next to me. Its not a fact of reaching the enemy spawn, the enemy spawn comes to you. Which of course adds on to the problem of painkiller, which never ever protects against spawn camping, like it should. It only creates more problems, by spawning players in with super health.
Even explosives in this game are just so random. Claymores, while still usefull if you plant them right, have been butchered so much. Stuns/flash disablement, lightweight bullshit I might add. Claymores weren't a problem in COD4. I don't know why IW decided they needed a nerf. Grenade launchers, I have watched hit the opposite side of the cover I'm using, only to penetrate and kill me. So now cover doesn't protect me against explosives? It has happened on more than enough occasion. I watch the killcams, I'm not being ignorant, I see the explosive land on the cover, on the opposite side I'm on. And it still kills me. Why is that IW?
The game on so many levels takes practically no skill whatsoever. The game will cut of your air, decide that its your time to go, because the game said so. MW2 isn't about outplaying the enemy. Its about using whatever you can to bring as much luck as possible in your favor, and hope you get a good killstreak reward. I know I am not the only one that gets incredibly inconsistent scores. Same lobby, one match I go 65-5, the next 11-8, are to takin a piss. I am aware of facing different skilled players, but I actually cannot judge how good I am at all, because every game its something different. Not because of me, and not because of the people I'm playing. Because of luck. And thats what this game has boiled down too. Luck.