I guess you've never experienced rdio? There we had a real thriving community of music lovers. Albums were discussed in comments under the item in questions, comments were rated, replies could be added. Popular and recent comments of your friends were featured on your frontpage. The heavy rotation section revealed a single users' (or a group for that matter) current taste at a glance, I could start any user's personal radio station.

Compared to that Spotify is a social tragedy - the activity tab has to be one of the most disappointing areas of the service. I can shout, but nobody can get back to me or discuss anything there.