That seems quite low indeed, but at the same time, these people played the song, not bought it. How much do the artists get paid then it's played on the radio? Is Spotify is rolling in dough and wasting it on extravagant and silly purchases or barely surviving? From my personal tracking of news, it seems the laters.
One thing I will tell you that is if Spotify will drastically raise prices, they will only fuel the increase of people turning back to pirating music, which currently almost doesn't exist, specifically because of Spotify, Pandora, and Youtube.