The way I use Spotify is I just use the "saved albums" feature, plus offline caching. This is how I like music: as objects called albums, which I "have" so I can browse and play them easily.
I feel like most music systems, Spotify too, does a kind of violence to the album structure, with all their playlists and shuffling and whatnot. The very idea of "streaming" is vaguely antithetical to the album structure and to the idea of possessing discrete artifacts... If I designed the perfect music player for me, it would almost be a kind of simulator of a record collection with a record player.
Anyway, I am also completely uninterested in Spotify's "social" features. I think their metadata interface is pretty poor and their "Related Artists" is totally haphazard compared to the actual musical knowledge embedded in databases like AllMusicGuide (which I adore).
I also get irrationally upset about Spotify's prominent display of what I call lifestyle propaganda, like their playlists of the day like "Saturday Beach Party Bonanza" or "Yoga Morning Zen Relaxathon" or whatever. (For some reason I never see "Technical Death Metal Tuesday" or "Zappaesque Hell Jazz Extravaganza" or "Lonely Bong Haze Headphone Friday".)
So I dream of a music player with another type of appeal, more album orientation, more facts and knowledge based relational metadata, and better catalogue curation (Spotify's artist pages are overloaded and unorganized and the metadata for classical and jazz especially are messy).