Without Musical Reinvention or Experimentation we wouldn't have The Beatles for starters - where on earth would we be without them? I'm certainly not suggesting Radiohead are as influential as The Beatles, but I would suggest for sure we would not have bands such as Coldplay, Oasis, or Muse without Radiohead "reinventing" their music (I would prefer evolving, but whatever). Electronic music, or modern day rock using elements of Electronic music would not exist or be modernly acceptable without Kid A - thats a fact (no one would have the guts to try it without risking dollars and/or credibility besides Radiohead).
Say what you want about them, but music would be at least 5 years behind where we are now without them.