The aspect of this that really bugs me is that people never get how revolutionary something was. Like taking your example of music, people listen to songs by The Beatles or Nirvana or David Bowie and think "Their fine, but I don't know what's so great about them - 100 other bands sound the same." But the thing is, at the time, no other bands sounded the same, they were just copied like crazy.

You see it with movies, too. Gone With The Wind, Citizen Kane, Double Indemnity, Blade Runner - all really good movies in their own right, but putting them in the context of the movies of the time shows how influential they were. All highly copied afterwards.