The only other gaming series that are run like CoD are the sports franchises. They both release yearly full-priced games that don't change anything in the big picture but make marginal balance changes and add a few superficial features. In the sports games you get updated rosters and seasons. In CoD you get a new single player campaign.
Comparing to Battlefield series, Batman, or Final Fantasy doesn't work for numerous reasons. The first being that there is long-term plan for any of those franchises. We all know that next year at this time there will be another CoD game about to release. Then the year after that... then the year after that, until there is a year that CoD doesn't sell as well as Activision wants it to. Other franchises develop one game at a time, mostly because their publishers aren't Activision (see Blizzard release schedules).
Also, the other games are usually dramatically different than their predecessor in some way. Battlefield 3 isn't from a gameplay perspective, but the technology underlying it is revolutionary compared to BF2 which came out over 6 years ago. Final Fantasy's have always been very unique from art style, to gameplay, to story-telling methods. I have not played Arkham City, but I understand they made the world more open, which could theoretically greatly alter the way the game plays. I'm assuming the combat is much improved from the simple one of Arkham Asylum as well but again, I don't know for sure.
At the very least CoD is on a yearly-release schedule which separates it from most other franchises, and I would argue that it's a completely different beast altogether.
BTW, I had a lot of fun with CoD4, but kit-based deathmatches aren't my thing, otherwise I would probably pick up the new one every other year maybe. It's really how much you can afford to play a game like this or how many other games you play a year, and I'm not trying to say people who buy every year are wrong.
