Why is Spotify better than iTunes?

So today I sat down and gave Spotify a good look. I'd tried the free service in the past and had sampled the upgrade on my iPad and iPhone for a few days, but I couldn't really figure out what was so much more appealing about it. After today, I still don't, so can someone who prefers it to iTunes explain why?

Near as I can tell, the benefits from a subscription membership include unlimited streaming and use on mobile devices. iTunes provides both of those with iTunes Match. If you aren't going to have access to wifi to stream with and you don't have a data plan that will allow lots of use, you can save your Spotify playlists for offline use. How is that any different from having the files saved in the music player on your mobile device? They're both going to be using memory, but one you'll own, the other you'll just be borrowing. It strikes me as a smarter move to spend the $10 a month to purchase an album or group of singles that will be yours as long as their format is supported, rather than pay it to listen to the radio, which I can do for free in a number of formats, including basic Spotify and Pandora. Spotify's PC app will synch with my playlists in iTunes on my Mac, but the mobile app doesn't see any of the songs on my iPad, which means I'd have to go through and make all those playlists again if I wanted them. And is there a way to mix my music in with the radio offerings? I've looked but can't find one. And does Spotify offer lyrics?

I understand the appeal of the free version, but I just don't get how renting music would be better than buying and owning it, especially with how unreliably located and priced data streaming options are. Is there something obvious I'm missing here? I'm on the one month free upgrade trial, but I just ain't seeing the magic here.