The problem is with the category, Hard Rock/Metal. Foo Fighters could be classified as Hard Rock, not very Hard Rock but stiff, well, semi rigid, starched then. Hard Rock and Metal are very different, their fans are worlds apart, yet they compete for one award?
The other extreme is to have the categories changed to things like "Best performance for a quasi-hard rock, all male member band featuring ex-Nirvana drummers" the nominees are: Foo Fighters, Foo Fighters, and Foo Fighters.
Do the Grammy's really matter? That album that they bring out every year with all the nominees always sucks. It's like they psychically know which songs irritate me most and put them on one album just to annoy me, specifically.