academic musical training is not for the hell of it. it serves a purpose and will give you insight unattainable elsewhere.
the few people i know who have serious compositional and theoretical chops--like, advanced degree level chops--are pretty self-effacing about music, probably because they have a feel for how little they know
there's no substitute for listening intently, and listening intently is a fine substitute for a minor in music performance
most people would absolutely hate - yes, you included - 20th century post-modernism in classical music. but post-modernism is being more and more frequently involved in the popular media of today.
the examples you have provided are trivial exactly b/c postmodernism isn't even a 'thing' anymore. it's woven into our cultural fabric. there's as much postmodernism in a mountain dew ad as there is in any pop lyric.
what radiohead does is fine. i don't have any major problems with them. but there's nothing tremendously new about it in the pop music arena. you don't have to go to boulez or xenakis or whomever to find antecedents for what they are doing. you just have to look outside the current top 100 over the last 20 years.
for people who are as forward-looking or more so, you can look within the top 100 today, if you are feelin' lazy. missy elliott is as innovative as radiohead, if not more so.