If it ain't broke don't fix it. People have loved, are loving, and will continue to love CoD because it always has that fast paced action arcade style multiplayer.
True. CoD has the best ratio for time fighting / time running around. It's fast paced and it's not particularly hard to kill something. If I have to do a quick game of something, I'd choose 2 games of CoD which includes me fighting continuously than a game of Battlefield 3, fighting for 10 seconds while I get to the map in 1 minute. Even if I do like Battlefield 3 more because of the different game style.
Though a good middle-point that I am also very satisfied with lately is Blacklight: Retribution. also
Warface is also going to be very pleasant in this theme once it comes out, the beta at least was great.