Personally I'm in the camp that LIKED second chance. Considering black ops OVERLY GENEROUS hit boxes and eager auto-targeting system, not everyone was a super James bond shot and get this, not EVERYONE slumps over dead from being shot in war. In fact, the U.S. armed forces are full of stories of guys (all wearing some sort of body armor mind you) of guys who were shot still returning fire on their enemies and even the enemy (who isn't wearing body armor) doing the same thing.
My thing is, it took the fast paced action of CoD and added something that added a pretty cool dynamic by forcing you to double check your kills and risk trying to get that kill shot only to be out of ammo when their pal comes around the corner. Also, it was a great way for newbie players (you know, the new customers the game was hoping to attract) or casual players to be able to get a few kills in and enjoy the game. I may be in a small minority by saying this, but getting your butt handed to you in map after map after map the first time I step into the multiplayer of a game doesn't encourage me to get better. It only encourages me to avoid the multiplayer altogether and to go play something else.
I'll openly admit to using second chance a lot when I first started, and as I got better I experimented with other perks (eventually I had pro in everything, it was fun to work specifically on the pros until I got them). Eventually I stopped using it altogether, but if it wasn't there I wouldn't have continued playing. Especially with the amount of smack talking in the game, that's a huge hurdle to overcome for new players coming into the game, and second chance kinda leveled the field a little bit.
Besides, the only people I ever heard complaining about second chance is people who were so busy running around trying to rack up kills that they didn't pay attention and got deaded by the guy they just shot and ran by. I actually felt a little bit of joy ruining people's streaks. Sorry that the feature ruined your fun of dominating every single map.
In fact, NOT having it in MW3 is one of the reasons I haven't bought it yet and I probably won't now that it's been out for a week and everyone is probably 100 times more badass than me and it's just going to be a non-stop grief-fest. It's my own personal protest. And luckily with Saints Row, Sky Rim, and soon Assassin's Creed Revelations, I won't miss it at all. And if it doesn't re-emerge in future CoD installments, they've lost me as a customer permanently. A man has to take a stand for what he believes in. I'd rather have a feature in a game and choose not to USE it if I don't like it than take it away from EVERYONE just to enhance my OWN personal experience.