This is a hard problem, and a lot of it (I think) is just platform immaturity, and hopefully it'll work itself out if we're all patient. But, here are my thoughts that arise from your query:

• I'm actually not much of a people person, so I don't really miss the "Happy Birthdays," but I think you're right that it's missing, and it's important to many people. Not sure how to encourage that, though. Groups?

• I've been thinking about the sharing vs. adding original content recently. One means of "adding value" is being the first to bring something to my attention. Curators (myself included) could get better at recognizing the value of having content delivered here from elsewhere on the web, even if the steemit share doesn't add any substance. It's the difference between ordering takeout or having pizza delivered, and convenience should be rewarded.

• I read an article at Bruce Schneier's blog recently, Stop Trying to Fix the User. Much of the curation here feels like that. For example: I get the concerns about plagiarism, and they're legitimate, but no one ever comments on my facebook posts asking me to cite the source of an image before they'll "Like" it. Not sure what to do about it, but the more you ask the authors to change, the less they'll be inclined to stay.

• Flag wars: There has to be a way to accomplish a reliable reputation system with a positive-value voting system. Abusive flagging creates an atmosphere of fear, even when I'm not the target (personally, I recently began unfollowing and declining to vote for posts by people who I notice that get involved in flag wars).

• Hostility towards bots. I haven't even spent much time working on bots, but the luddite-like attitude towards bots here really puts me off. As I posted here, I think that bots will eventually be steemit's greatest strength. I wish people would just be patient, let them work through the speed bumps, and wait for them to amaze us all. Developers should try to curb abuse - whether human or bot, but shouldn't be actively trying to discourage bot deployment - not even voting bots. It's like saying that google should employ an army of humans to replace its PageRank algorithm.

Dunno. Just thinking out loud, since you asked, and since I agree that user retention is an important goal at this time in steemit's lifecycle. Those are my thoughts, for whatever they're worth.

PS - Happy Anniversary!