Funny, I was just reading an article last week about the currently hot, producer extraordinaire Jon Brion.
He was quoted on a similar question as follows:
"Why do I love songs? It's three minutes of condensed storytelling, of trying to collect your thoughts lyrically, musically and emotionally, and when it works there's nothing on earth like it," Brion says. "Think about it: Airwaves of sound move the little hairs and bones in your body, enter your brain and make your neurons fire off skyrockets. No matter how much you look at the math of it, it is beautiful, it is mystical beyond words. I only have to think about a song like (The Kinks')`Waterloo Sunset,' and my physiology changes. What's not to love about that?"
A little new-agey, but that explantion (and most anything written by Ray Davies..)works for me...
Tim