Good question and I suspect that you've answered it in the asking -

The reasons you cite are all valid and all equally possible, for me anyway. Music tends to provide a soundtrack to our lives. You remember songs from your youth that have special meaning. I mean, I still smack a beat on the steering wheel when a rare Foghat song comes on the radio. Why? I mean, I'm not a 15 year old kid in high school being pushed on by that beat that was just soooo cool then. Neil Young was there in the park at night when were partying up, drinking and chatting up the girls. The B-52's and such drove us, a bunch of non-rythmic, up-tight suburban kids onto the dance floor...Zep was blaring from the radio when were sitting in a friends basement plotting on putting a band together....

And some music does inspire- I find it more and more true every day. I hear things now that I may have dismissed before and listen in a way I never listened to before. Country music, funk, old R&B, swing, jazz...there's always something in everything that can inspire.

Heck, I bought a Django Reinhardt collection a few months back. Before I became interested in learning to play guitar, I would have never listened to it and if I had, God forbid, would not have enjoyed it. Now I listen to it and I'm stunned at how the man could play!

Plus, you gotta remember, some peoples tastes narrow as they age but I've found from my musician friends, that their tastes seem to expand as they age. I suspect that even when I hit my 80's, I will still sneak away to the community room at the Sunny Hill Retirement Home and pop on 'Little Wing' and still feel the chills listening to Jimi hit notes that seem to wrap around the soul. Or maybe I'll turn down the lights, pop my medication and crank up Metallica on whatever portable music system we're listening to at that time.

Point is, music, like art, is very personal and what you like or don't really like has no real rhyme or reason.

It's whatever speaks to your soul.