There was an idea which you find in a lot of music-appreciation books that music evolves from primitive music to better music - perhaps this reached its fullest expression in Wagner's circle. This was associated with a whole lot of proto-fascist ideas, and it wasn't just academic ethnomusicologists in the US who had a problem with it. (Victor Zuckerkandl's "Sound and Symbol" - cheap paperback from Dover, if you're curious - argues an anti-evolutionist standpoint which he presumably formulated when living as a Jew under the Nazis. He's surprisingly quiet and moderate about it, considering).

The evolution of tunes (or temporal change, to be more neutral about it) doesn't carry anything like those associations. You don't need to see it as a progression from the primordial pentatonic slime to ripplingly muscular blonde beast sonata forms pulsing with Dynamic Tension and kicking sand in the faces of music from inferior cultures, and hardly anybody does.

What the categorization of tunes (and other musical elements) does sometimes help with is decoding their history. Bartok did that and wasn't anybody's idea of a Nazi. The conclusions you get from that sort of comparison, as with DNA sequencing of modern populations, don't help the nationalist case one little bit. Usually everything comes from somewhere else and you pinched it from the smelly gits you most despise.