W&S - I'm not sure what leads you to leap to the conclusion that becasue a "middle-aged" person wears a Police t-shirt they are "reliving their youth through a band."
Perhaps they're just feeling nostalgic. There's quite a difference there. I saw the Police when I was 15 - I'd be a liar to say that the reunion didn't make me feel a bit nostalgic for those days when most stories began with "here, hold my beer and watch this." But that doesn't mean I'm living in the past. I think a lot of us on this forum are not necessarily looking back but rather looking around - if that makes any sense.
Along the lines of what Sockii said, I think most of this is just escapism. Nothing wrong with that (unless, of course, it hampers your day to day life in the real world). Whether you're a music fan, movie fan, sports fan, etc. it's all good with me.
And you're right: it's damn good music!