You make good points, but you're not going to be able to apply these ideas to most pieces by Chopin, Liszt, or Beethoven. The Nocturne in E-flat is an exception; there is even an alternate version written by Chopin himself with much more florid embellishments. I would also see no issues with using Liszt's opera paraphrases or Hungarian Rhapsodies as basis for improvisation, and many pianists have. They are fun pieces born out of the improvisatory tradition, and making modifications to the music on the fly is in the same spirit with which he conceived it.

But, much of these same composers' output is the result of years of refinement and hard work. Liszt's Transcendental Etudes have their germ in a work he wrote as a teenager; over the course of 26 years, he revised and elaborated on them several times to arrive at the set we know today. What choice does one have but to respect that and play the music as written? And would you really want to change anything in Chopin's Preludes? I wouldn't.

I reacted to your post the way I did because I've had to play an awful lot of bad pop music. I gag a little whenever I see guitar tabs. If you give me a lead sheet or anything that is less than fully fleshed out, I will refuse to play it. It's not my job to compose on the behalf of songwriters who have no ability to write music.

Heӏӏ is censored, so it is converted to heck.

I think the question is why? It censors, or converts he*l, but it has no problem with 4 of George Carlin's 7 dirty words. Very peculiar.

And no, I'm not going to prove it.

Yes, it is funny it should be censored, while worse words are not.