Hmm. Okay, I have two different ways to answer this. Right up front I'll say that as an author, I try to respond to each piece of feedback, even with that annoyingly same 'thank you for the feedback'.

As a reader? I honestly don't care if the author responds to my feedback, unless it's really detailed and I *ask a question*. Mostly I feel that if they owe me anything at all, they've already done their duty by providing me with entertainment and I'm *thanking* them for that by giving them feedback. They've already given me what I want. I don't need to be singled out and given their attention as well.

I don't practice this with responses to my own writing, though, so I'm not sure how strongly I believe that authors don't owe their readers anything that they haven't already given. Or maybe it's that I'm just bowing to the expectations and wants of others to avoid pissing people off. I do know for sure that as a reader I'm thankful for the story and expecting anything else just seems greedy, imho. Especially when it brings writers beyond their comfort zone, if they feel stupid responding to fifty comments with the same line and it wipes them out to think of something new and original to say to each of those fifty or more comments.

I'd rather they write another story than reply to me with something witty.