I'd agree with your assumption that you might be missing something here.
This may or may not change your views on Steve's chops of the lack of them http://www.youtube.com/watch?v=6hUGKu5WwrA
, but history will tell you that Steve was the
definitive drummer of his time, and like all greats do, he put his stamp on the music of that time, and influenced an entire generation of players.
As Pat says, Dave Weckl & Vinnie both, have cited Gadd as a major influence in their playing and Gadd had a lot to do with the way they play and sound, today.
So there's them apples : )