A few defenses, then my own opinion:
AC is not a milked franchise. You define a milked franchise as a series of games (or brands), where something to do with it is released and no new innovations occur. This immediately takes AC and Halo out of the picture: Each Assasins Creed game has added something new (and the 3 main console games really can't be considered "milked"), such as the momentum-based gameplay in AC II: Discovery. Halo, on the other hand, had released the first three for the purpose of the story, and most of the spin-offs to either expand the universe or experiment with and refine new concepts. Halo Wars was an experiment with turning Halo into an RTS. Not that much of a success. ODST wasn't that good either, and was really more for big fans of the Halo franchise, as it was mostly made for players to experience what it was like for you if you DIDN'T happen to be an incredibly lucky super-soldier. As far as Reach, I think that game was mostly a test for the new versions of Forge and Firefight, and to test the waters with the Armor Abilities. As far as the new trilogy... let's wait and see, before we judge. (Though the grenade pistol looks cool XD)
So my thoughs on milked franchises:
1: Call of Duty, SORT OF. While the more recent games haven't added much (the COD points don't count), they ARE an improvement from some of the earlier games. WaW is still king of that franchise, IMO. (REZNOV FOR THE WIN!)
2: Lego. The few Lego games have been mundane, and never added anything new. They had a certain comic element to them, but they are still poor quality. As one of the top toymakers in the world, with plenty of funds, they could do better.
3: NOT Madden. You can't give people new stuff unless the rules of the sports changed.
4: Heroes of Might and Magic. Bet ya didn't see that one coming. The games have been around for a long time, and they have yet to get past the idea that turn-based RTS's do NOT work well in multiplayer settings.
5: Mario, Sonic, Zelda, Kirby.... Pretty much anything that came over in the Gaming Revolution of 1985. Heck, you could even add in the more recent Final Fantasy and Pokemon series!
6: Fallout. They just don't know where to go with this series. They should find SOME way to wrap the whole thing up. It doesn't make sense to leave the world of Fallout in a nuclear wasteland for all eternity.
7: Oregon Trail: It's been I think 5 or so games, and it's always the same thing: Has died of Dissentary
8: YuGiOh: Again, quite a few games, nothing new.
I could go on and on, but I'll settle with those for now. Fire away, Escapist community.