But yeah, you are renting the music from them so you have to give it back the way you found it. I don't really consider spotify a music player of the same sort as winamp or foobar2000, it's much more like radio where you have agency over the playlist rather than a local executable to manage and play your local files.
It would be interesting if they provided some a way to get an audio stream you can then further process for replay gain and other stuff, though honestly fiddling with all that stuff seems like busy work.
Library available to outside of Japan is significantly larger on Spotify compared to everyone else. It looks like some tracks are blocked outside of Japan, but compared to other services, this phenomenon is a lot less, actually magnitude less common compared to, say, Google's offering. (Haven't really done extensive research for Apple but doing a quick search, it's not very promising...)
I don't know what making this different, but as far as this relatively small segment of music, certainly Spotify's doing this right.
Actually, this convincing the big players to centralise is the real value Spotify provides, and this picture of them being a technology company could be viewed as smoke to obscure that they are basically an IP management company (though I expect the music industry is well aware of this and made contracts that reflect this).
Classic interception attack
They say "Spytify records the same quality that Spotify outputs" but that implies a loss in quality if it's recording an mp3 and re-saving it as a new mp3. There's no lossless option in Spotify.
Thats like saying the only thing McDonald's french fries have going for them is that they taste good and are cheap.
It also might be that you haven't liked/listened enough for it to be useful yet.
OTOH when I used google play for a few months, they managed to recommend a new to me band that was based in roughly the same area and playing the type of music I listened to.
So at least for that type of music, they were a lot better than anything I've ever got in multiple years of using spotify
Uploading your own music sucks (unreleased tracks get blocked for some reason), tags are messy (there is no standard, the labels do whatever they want), you can't customize your listening experience at all (no replay gain, dynamic playlists, custom tags or equalization) and obviously not owning your collection (which admittedly is irrelevant for most people).