You know, while you have a point, I have a counterpoint.
If you "buy" songs -- you don't really own them either. Well, you own them insofar as you can play them DRM'd on your current system. If you buy songs at 99 cents on ITunes, you are stuck with ITunes and iPod, period. Unless you do crazy things like burn to wav files and all that crap.
With subscriptions, if you see yourself spending $400-$500/yr on music, then maybe a lifetime of subscription is better. I mean when you're dead, are you going to pass on your music to your children -- and by that time the whole system will have changed anyway, it won't matter.
It all depends on the type of listener you are and how many songs you like to listen to.