Actually, they put the Call of Duty name back on Modern Warfare 2. I don't think that they ever officially announced that they were going to leave it off; they just released a few images and a trailer that just said "Modern Warfare 2" so everyone started assuming that they were just going to call it that.You must admit that modern warfare was a fantastic game, and many others will agree. The reason why they are calling the new one just "Modern Warfare 2" is simply because the first was so successful they can do without the Call of Duty branding and it can be it's own series of games. MW2 is going to be a sequel, the first sequel seen in the whole series of Call of Duty.
I agree. Treyarch failed miserably with CoD 3 and only really succeeded with CoD WaW because they didn't have to do the majority of the work; the game engine was already made by Infinity Ward.. all they had to do was modify it to be WWII instead of Modern Warfare.So I only get excited about a new Call of Duty game when Infinity Ward develop it haha