It is a total immersion in one typical German estheticism, based on the glorification of everything German. He was a fierce Judenhasser. Everyone should listen to his music as much as possible. Therefor, and for many other reasons, playing Wagner is not possible in Israel. What a wast of time and creativity.
Music becomes Jewish when the expression is Jewish.
It doensn't always have to be a chazzanut or a composition of a Jewish composer. Blessed art Thou, Lord our God, King of the universe, who sanctified us by His commandements and has given us the ability to enjoy music. I always say this bracha when I pick up my violin but never when I do so to play Wagner. I found your article in the Liberal-Judaism v7n146 very interesting. We have to be specific, e.g. music composed by Jews, Jewish liturgical music, Hebrew music, Yiddish music, Ladino music etc.