Yea, that isn't it at all. Pandora has been on the brink of bankruptcy for years. This is a new start to try and make the business work by figuring out their licensing cost structure.
That's one way of looking at it. Another is that there's about to be a big fight over royalties to the labels with Apple entering with a huge salvo today[1], and Pandora likely needs a new face in order to join the battle differently than they had in the past. In other words, "circumstances dictate."
Interesting. If that's not enough royalties, Spotify is charging too little. According to last.fm (who can record all track plays from Spotify), I've played 10672 tracks over the last 4 months ($55 in royalties at the 0.0052/stream rate), but paid $61.9 to Spotify for their highest premium subscription in the same time.
Pandora pays CRB rates, Spotify negotiates direct licenses with labels. They both pay out over half of their total revenues, which of course is unsustainable. Pretty much all music services are surviving off of capital infusions while keeping the price point for subscriptions palatable to the consumer. Eventually we'll see some of them pinched out of existence, unless Apple's muscle has an effect.