Agreed. On a more objective level (as objective as you can get about something like this), they weren't *that* popular for more than a few years, their fame rose and fell very quickly... and they only released two albums that the mainstream really knew about. Only people out to hear all MCR music have heard the first album, and Danger Days didn't do nearly as well as the previous two.But MCR was far from being one of the best bands of the 2000s.
As far as influence, I think they were as influential as any other fairly mainstream band. I definitely don't see them as being more influential than other bands of that time period with the same amount of success.