Something I realised recently: music can be incredibly complex, but basically it is either loud or quiet, high or low, fast or slow, and degrees in between. Listening to and playing music for more than 30 years has led me, perhaps unconsciously, to that awareness. And it's as true for so-called classical music, with its elaborate structures and harmonies, as it is for the harmonically much more simple forms of popular music. Hardly an earth-shattering epiphany, but it probably explains why certain kinds of music that I used to find harder to listen to, like Benjamin Britten, now give me a lot of pleasure.
Another reason why I now love the music of some composers that I once found incomprehensible: the voice. Looking back, I realise that I always loved opera long before I became absorbed by instrumental music. Even when I listened mainly to people like Prince, Bob Dylan, The Smiths, or Robert Johnson, what I responded to most was not the tunes or the instrumentals so much as the expressiveness of their voices. And with operatic voices, the more operas one listens to, the more one trusts the beauty of the voices to accustom one to unusual harmonic patterns. Hence, Benjamin Britten and Richard Strauss are rhapsodically gorgeous to my ear, when thirty years ago I probably wouldn't even have recognised it as anything more than sound.
Proof that this is all a question of taste/exposure: a few years ago, when I was teaching in Prague, a colleague (who was more of a jazz man) told us that the previous evening he had attended a performance of Puccini's "Tosca" at the National Opera. When I asked if he liked it, he said he did, even though (quote) "there weren't many tunes in it." Just think about that: No Tunes. In Tosca. By PUCCINI. I'm not saying that he was an idiot. I'm saying that I take this as a lesson for myself, because there are operas by Alban Berg, Bartok, even Wagner, that I may come to like one day, just by putting aside the impulse to seek out the regular melodic patterns that the ear most naturally responds to, and instead follow what the music is doing, in relation to the story.