I am not sure how I feel about your conclusion, but it is definitely something to think on. I definitely agree with your premise; standing still doesn't have to imply stagnation, and there are absolutely things that do not need to be improved.

(I would disagree on one relatively minor point: you wrote "Art and music are to stir the mind, touch the heart and please the senses. Any art or music that doesn't do all three of those things for somebody--preferably for lots of somebodies--has progressed beyond the point where it's art or music at all." I would amend that to "any art or music that doesn't do at least one of those things, preferably two", rather than requiring all three.)