More objections to Spotify

Here's a BBC News page with a segment from a recent Newsnight programme discussing Spotify and whether it does artists a disservice - Spotify - friend or foe of musicians? We still see the issue of low royalty rates for the musicians, but increased ticket sales as a consequence of exposure via Spotify is mentioned as a bonus. But, at the risk of sounding like a stuck record (!), why has no-one actually looked into the effect of music-streaming services on music purchases? Perhaps I am an oddity who buys more because I can listen first, and extensively before buying an album? The internet offers a hugely diverse route into finding music, particularly the social aspects of last.fm, Spotify, Bandcamp and Soundcloud (all of which I use), and many others I don't have time for. Maybe this isn't all about piracy, lost sales and the like but is a new way of business that needs to be grappled with.