Some way I expected reactions like yours, still I don’t understand. Funny that your first two sentences about Piazzolla can be said about a lot of musicians, Bach for instance. The fact that Bach’s music has received so many different performances and interpretations (from Gustav Leonhardt to Wendy Carlos) and has been the object of recurrent “revivals” in the history, just witnesses of its universality.
You are entitled to your personal tastes but It seems to me that you go beyond, implying that Piazzolla’s music is inherently “poor”, mere fashion or irrelevant.
Personally I do not like very much the music of Schumann, Mendelssohn and Brahms but I can’t deny their role in the music history. Piazzolla is not Bach, off course, but his music deserve the place that has acquired trascending the limits of the musical genre.