An interesting post that poses an interesting question - has punk or disco had the more lasting impact on music and pop culture?
My contribution to the discussion can be found in the comments, but there's one thing I want to add, in response to the notion (early in the post) that by the mid-seventies, pop music had become corporate, safe and bland. There is some truth to that, but there was also some great music being made during that period. A couple of months ago I made a tape to listen to in the car of music released in 1975, which included songs from the following albums:
Born to Run, Bruce Springsteen
Blood on the Tracks, Bob Dylan
Tonight's the Night, Neil Young
Siren, Roxy Music
Horses, Patti Smith
Katy Lied, Steely Dan
Young Americans, David Bowie
Physical Graffiti, Led Zeppelin
Certainly, a lot of those artists had been around for a while, but that's not a bad list - and that wasn't even all of it. The moral of the story is that even in the worst of times, there's some pretty darn good stuff waiting to be found.