Without disagreeing with anything that has been posted to this thread, or
at least understanding the feelings of all who have posted to this thread,
let me just throw these eyes of newt into the cauldron:

Wagner's music is considered profound and inspired by some; less so by
others...as is the music of many others.  (Even Mozart finds less than
unanimous appreciation on Internet classical music lists!)

While probably not the libertine some claim him to have been, Wagner did
seduce another person's wife, and later marry her, conduct that some might
find more reprehensible than others.

Wagner was guilty of some horrendous anti-Semitic utterances, many if
not all in disproportionate reaction to his feeling of having been dissed
by Meyerbeer.  I cannot imagine Wagner being the only nineteenth century
composer who made anti-Semitic statements; others may have been more
private.  That anti-Semitism was not unique to Wagner in the musical world
of that time might be evidenced in the prohibition of Adam's "Oh holy
night" as a Christmas song because Adam was Jewish.  Mahler had to convert
to Christianity to obtain a conducting job in Vienna.  On the other hand,
the premiere of *Parsifal* was conducted by Hermann Levi.

What people cannot forgive Wagner is something for which, ironically,
he cannot be held responsible.  He became the darling, long after his
death, of Hitler, and his Nazi henchmen, who exploited his manifested
anti-Semitism and made Bayreuth as much a shrine to National Socialism
as to Wagner himself.

Walter Meyer