Which also presumes that I cannot enjoy anything non-metal, and I can assure you that is far from the case. For times sake, I'll spare you the fairly long list of non-metal things I can enjoy (though I think my Zappa fandom has been fairly well documented).
I've just always heard over the years how great those two were (though I understand part of Lennon's deification coming from his unfortunate death) and I don't get either one.
Oh, btw Banky, I do at least understand the appeal of the Beatles, but I still don't like most of their stuff.