I think the only people that are really angry about Spotify are the artists. It seems like the way their payments are calculated, they get the short end of the stick.
Artists don't get a 10% cut each time a song is played on Spotify. The only people getting rich with Spotify is Spotify and the label that grants the content rights. The artists do get almost nothing.
- if artists demand too much payment from labels, labels won't sign them
- if labels demand too much from spotify, spotify won't sign them
- if spotify doesn't sign enough labels or pays too much to them, it will die either due to not enough music or not enough revenue to find growth.