Music has mainly been about ideas. Ideas translated into an ordering of sounds (pitches for the most part). Unless there is a common pseudo-language through which people can eventually grow meanings, like tonality was, ordered sounds cannot convey ideas. Although it's sometimes floating around like a dream (nightmares mostly), tonality ceased to be an artistic possibility a long time ago. Unfortunately most composers still believe ideas can be perfectly channeled through sound, a belief that has secretly transformed itself into making order in music the main idea. And so, countless "personal" systems of music-making have flourished over the last century.
It seems that composition has been involved in a blind (or rather, deaf) search for meaning: looking for order (even if trying to convey chaos) as if meanings and ideas were to spring from the nonsense. When disillusioned, the next logical step appears to be backwards to the past or to a postmodern limbo, being cynical about the impossibility of artistic creation.
Stubbornness in maintaining semantic order above all else has prevented a great deal of composers from opening their ears and listening. Of course, many have impeccable hearing, but the problem lies in what they're listening to. It might be that most want to dissect what they hear into combinable parts.
More than having the power to convey ideas, sound itself (with its movement and transformations) has the potential of establishing equivalencies. To what? To reality and to the individual psyche. This is of course nothing new, great artists have known this all along. But it's easier to infuse some logic to composition, as opposed to dealing with the diffuse and ephemeral raw matter that is sound. That's why true art (not art that's correct) is a rare thing, always has been.