This obsessive fear of redundancy to me is a carry-over from the post-war years when the artistic community as a whole had no patience for anything except that which was perceived as avant-garde. There is so much desperation in the music of that time and a lot of it is so original it literally hurts. Worse yet, this conquest for unexplored terrain is more often than not a shield that the mediocre can hide behind due to the fact that the premise of modern art makes it basically impervious to criticism (it is very Emperor's New Clothes). It's easy to avoid developing the necessary skills needed to be a competent composer when all you need to do is obfuscate your art enough so that it appears to have depth. Great composers that create works with an appealing style as well as rock solid architecture have nothing to fear from the ghosts of the past. It's of course necessary not to repeat things that you have heard verbatim because if you don't add anything personal there is no point in composing in the first place. I find that the separation between novice and master is most striking in the variation form, where you can't really hide behind anything.