I'm not sure I get the public access thing. One of the turn-offs of Tumblr (as a personal blog) for me was the lack of having that option. And considering how many private or small-scale spats end up going viral there, with everybody on the site needing to throw their two cents in having at least the option of privacy control might not be a bad idea. Granted, given the nature of the platform one could argue that it's the users' fault for posting sensitive info in the first place, but by and large here we're talking about teenagers. Dumb kids who are going to regret all this later in life and are entirely unable to do damage control. At least make privacy control an option.

Re: fanart, this is one reason I'm one of the dinosaurs who didn't jump ship from deviantART to Tumblr. Because I can keep track of my own art and the art I like. People suddenly started posting exclusively to Tumblr, which makes negative sense to me. You already had a perfectly good artists' platform! Ah well. It should only be a matter of time until they come back? '~'