You seem to be ambivalent about dissonance. At least you like Bach and Chopin

Indeed, they are the masters of extreme dissonance within the functional system. No one else even comes close...those who use as much dissonance tend to break the rules, and those who follow the rules tend to use much less dissonance. I'm not ambivalent about dissonance at all, really...I just think that dissonance without consonance for context is just noise. The language of music is dissonance and resolution. Mozart has a very limited vocabulary; Schoenberg speaks gibberish. Mathematically-configured gibberish, to be sure, but still gibberish. Bach and Chopin are poets.

Some of the late Beethoven must have escaped you... And the rest of your rant has remained unchallenged so far?!

I've played some of the late Beethoven, as you know. It's more harmonically complex than most of his earlier stuff, but still nothing quite on the level of Bach and Chopin IMO. Perhaps you had a specific example in mind? That's usually what is required to 'challenge' statements like mine.

Who's idea would that have been? I have never heard of that philosophy. I guess I know what you dislike about 20th century music, but it has certainly nothing to do with an increased occurence of dissonances.

It's something I picked up on in music school. No one's got the philosophy written out as such - at least, not as it pertains to the entire music academy (others such as Schoenberg have written as much explicitly) - but you pick it up in the attitudes toward functional music among the academicians, especially functional music that was written in the 20th century. (Not just the academicians at my school, but those doing research in the field as well.)

Oh yes, I remember Schönberg states something like that explicitly ("emancipation of dissonance"). I just stumbled a bit about you saying "most of the 20th century", because I would think that Schönberg and the tradition he has started (Berg,Webern,Boulez,Stockhausen,...) is just one single "phenomenon" within 20th century music. I think many people have basically only the second Viennese school and its followers in mind when they read the term "20th century music". Which is sad. I would think that even a radical guy like John Cage would never have said that he prefered dissonant sounds (on the other hand, it seems that for him all things were equal anyway).

There's a large number of composers represented here at PS (Poulenc one of the more prominent examples) who obviously did not follow the philosophy of "more dissonance".

Ah, and regarding the pet hates, at this moment only one thing comes to my mind (but this is hate clearly):
-> Mahler symphonies (and basically most of the "late-romantic" symphonies, also Bruckner etc.)

More people in the orchestra do not make for better music.

Indeed, though the influence is far-reaching despite the relative lack of devoted followers of the 'second Viennese school'. Again, it's just an attitude I've picked up on. Poulenc is connected to the 'old era' via Debussy, and doesn't often get lumped in with those 'attitudes' I was talking about. He was dead before the attitudes really took hold in the academy, as far as I can tell.