It's not Ezio himself, it's the fact that they feel they need to stretch him over 3 games but personally I looked forward to their initial vision which was to take you all over the world in different periods of time.
After the first game I couldn't wait for one potentially in the far east but obviously the 'Ezio period' is a massive cash cow to them.
Having not played Revelations I agree with you that he was better in Brotherhood.
I agree, even though I'm not sure about Revelations anymore. ;o;