While AW will likely be the largest overhaul since MW, Black Ops 1 was completely different than MW2 in many ways, and Black Ops 2 was completely different than any before it.
What makes it milking? Call of Duty has released a game every year since 2003, each game different from the last, each game successful.
If NRS split into two teams so they could release MK games on a more regular schedule, once a year, would you consider them milking the Mortal Kombat franchise?
I don't think creating genuinely different and unique feeling sequels when there is an obvious demand for them is milking, I do think nickel and diming the scraps of something over a period of time is, and COD is not doing that. The only thing i'd consider milking in COD is how hard they try to push their DLC maps.
I'd use the SF4 series as an example of milking, but i'm not sure if that's fair.
I do appreciate you giving a legitimate response, btw.