radiohead makes dismal, quirky original music that a lot of people (who hate radio cheese) enjoy. Not incredible musicians, but not bad.
Def leppard guitarist was average by any era - but it's about writing good songs, and he did that. There were guys who played 100x better, way more skill, sitting in their trailers still playing for free.
there's always going to be a better guitarist out there. Satriani, I was listening to his new wormhole cd last night, it's not technically unreal or impossible, it's just easy listening guitar instrumental that's more catchy and memorable than technical.