I just think that on the whole... Iron Man 2 has had an aura of disappointment settle over it.
There's just something about the movie as an overall experience (anticipation, marketing, that all important first trailer, the final product, waiting for the home video release) that all seemed incredibly lackluster.
Jon Favreav leaving adds to this sense of disappointment... I know the numbers don't lie (the box office was more than healthy), but I expected so much more from this film.
Iron Man 2
... It came and it went.
So perhaps this is good news.