> The story with Beethoven is not very different, ultimately some of the simplest pieces of his were the most popular and he wasn't very happy about that.

I'm sure many artists fall into the trap of 'the public likes the work I like least'. That doesn't make the work not part of the authors creation. For example, Raffi makes extremely popular (and actually pretty good) music and I'm sure he absolutely hates having to play it over and over again. Still a better artist than Schoenberg.