I personally enjoy all the Call of Duty games, each for its charm. I agree, the company does rehash a lot of the gameplay, but what about sports games? I mean those games have practically the same gameplay for about 10 years now. No one makes a big deal about it, for a simple reason. People like repetition, if it is still fun. Fun is all that matters in those types of games. When I am tired, and open up Mw2, I don't ever think "Oh man, I wish those models were different than Mw1. I just have fun. I welcome a million of those CoD releases, as well as Battlefield ones, because honestly, I think they are completely different games, and they both are great. They do not kill gaming. Informed people still buy them, which means they enjoy them.
Indie games are on the rise, so creativity is not looked down upon. Activision just has the cash to make such kind of productions.
In conclusion, I see the CoD and Battlefield series as a whole. I enjoy small touches and differences between the games, while keeping the same style, allowing you to apply the same tactics you already have mastered from a previous game.
The competition goes on guys..