If Activision doesn't change anything the production value won't go up. Call of Duty was stagnating once, after the release of CoD 3 and then they made the series what it is today with CoD4. The problem is that right now Call of Duty are still breaking numerous records for sales and if that doesn't stop then unfortunately Activision won't need to change it. At least they did include dedicated servers in MW3 PC, but that's probably only a decision they made because they know it will make them more money.
Woah, woah, woah. Activision did not make CoD what it is today, Infinity Ward did. They were given at least some creative reign over CoD4 and changed the modern FPS era. Then what happened? It made money, so Activision milked it and still are. Now they've alienated IW away from their company to a rival who's trying to hit the very market CoD dominates. (BF3, new IW IP). Do you even realise what stagnating means? For the past pages you've said "Activision shouldn't change anything because then it wouldn't be CoD". You're admitting to the series stagnating in those sentences and then arguing against it. I've played every CoD since CoD4 as the main game I played multiplayer on, and I didn't even really care about the single player, yet I still think it's getting tedious and boring. That's what lack of innovation and development does, people WILL get bored of the same old. Why do you think manufactured pop artists have relatively short careers whereas the truly innovative musicians make their careers go almost endlessly?
CoD4 is still by far the best game of the series to come out in this current generation, after the first few weeks of a new CoD I've always gone back to it. And your comment about it breaking sales records means nothing. Justin Bieber breaks records, does that mean he's the best thing to happen to music?