If it was about the ads, then they'd tie the API access to the user account, and require a user to sub to Gold for the ability to use third-party clients, then ads wouldn't be necessary in the third-party clients. This just goes to show that advertising itself is out of control - either they make more money off ads than they do subscription revenue, or it's purely about control. Money and control are two sides of the exact same coin, so either way you look at it, this is pure greed.