Sure, it's nice to get answer from the author back, but I don't really feel I'm entitled to get back a russian novel or even a thank you for each I loved the story OMG - so hot!! I comment with.
I much prefer author brainstorming for another story or delicious manipulation.

Entitlement of any sort is offputting to me, whether on the reader or writer ends of the scale. It seems like a lot of authors respond in kind to the feedback they get, with longer feedback leading to longer responses. I can't help but enjoy this, because it seems like it can definitely lead to een more discussion and sometimes new plot bunnies or tighter characterization and more creativity. I don't think any author has to respond to feedback, but it's always seemed the polite thing to do.

And a complete word to what you said about ljers picking and choosing who they respond to. It annoys me because if those are the only people they want to interact with, why don't they just set up filters and lock everything down to just those people? Why have an open journal if you're not actually interested in interacting with the people who read it?