It has everything to do with the music, the aesthetic, and nothing else. God knows some other great composers who wrote music which transports many to this day were less than pleasant persons. So, take it for granted, for me, the artist is forever separate from the art.
[I have first hand experience at 'what can come out' compared to 'what / who I am' -- and have many times heard much the same from others who compose.]
Wagner's music does not 'breathe' much. He had a notion of 'endless melody' but forgot that normally, people take a breath: there are natural 'pauses' which make speech that much more speech-like and believable which (imo) are almost entirely absent in the majority of his works.
The seemingly endless sequencing, which is often present, is a technique which in general has me jumping ship if that ship has much of the commodity aboard. That sequencing is the very fundamental premise of Tristan -- an evening laden with sequencing. [As a friend of mine commented upon a two hour Riverdance broadcast, "Imagine, two hours of
that!"]
I 'judge' any and all vocal music (any genre or format) first only on its musical content, and only long after on its textual content and intent and then if the goal of incorporating the two elements is 'successful,'
I only consider text -- at all -- if and only if the music and only the music has pulled me in via its 'import.' For a vocal work, anything less than the music first 'drawing you in and giving you some of the emotional import' without knowing a thing of or about the text, I consider a fail.
There is much in Wagner's scores which is remarkable. There is much I find tedious: far too much sequencing; in the orchestration often endless arpeggiation in the strings, the strings often treated more as 'padding' in general; in the writing itself, very little counterpoint (which I have a preference for, regardless of 'what genre' that counterpoint is or how it is used).
I think Tristan is a masterwork, a wholly effective score, and one hell of a wringer as a piece of musical theater. The Ring just does not 'carry me' for an instant. I very much like and admire his one abstract (absolute) chamber orchestral piece, "Siegfried's Idyll," because of its abstractness of form, the lack of any real literal reference, and its clarity. I would like Wagner more if he had pursued this avenue of musical thought more often. (Siegfried Idyll, too, is a "masterwork.")
Wagner, did, historically, expand tonality to an extreme, the first true and superbly accomplished use of progressive tonality, an extended music dialogue which avoids cadences, his more than intelligent handling of a high chromaticism. Without the fact of Wagner, later music would not have happened as it did, the 'busting' of common practice tonality, chord function, and high chromaticism are all present and accounted for in Wagner.
To the textual aspect: I find all of the ring 'just too silly.' There is "silly" in a lot of opera, nearly a convention where we are asked to suspend reality and accept what is there presented. A long aria, and that a virtuoso display, from a heroine in the very last throes of tuberculosis being just one of many more 'unbelievable' moments found in the genre. A not so due-to-syphilis crazed Nero in Monteverdi -- occasions of theatrical lunacy or historically inaccurate libretti are plentiful. Wagner's
mosh on the ring legend is, for me, truly a mosh, and very difficult to take seriously as theater.
Wagner's aesthetic (not mine, admittedly) pervades all his other scores -- as should be expected and as they should be -- of course then they are still filled too with all those aspects of the music itself which just 'do not work for me.'
Genius issues aside, I think Wagner had a very 'bourgeois' sense of theater and drama, and that, for the most part, was his audience of the time. He was, in his own time, remarkably forward looking in what music and music theater could be, while at the same time -- again for me -- there is something horribly banal about the subject and its dramatic treatment, reflected in an 'Average Joe' taste for the cheesier more commonplace theater tricks / schtick (i.e. what is 'dramatic?') and that pervades much of the music... That
"Leitmotif" business, to me is painfully simplistic, banal and... well, I agree with Debussy, who likened the device to
"A musical phone directory." Wagner, in his 'banality' as I think of 'banal', was consistent
All the above should demonstrate, I hope, two things.
1.) A lot of reaction for or against any composer's work is ultimately a matter of personal preference.
2.) There is no problem or dichotomy in not caring for (despising, even) a composers work while still being able to fully acknowledge that composer had the greatest of skill, and that they were one of 'the great ones.'