I am thinking what Steemit is missing to be a complete full service site is an Instant Messaging System able to send and receive private messages to each other. Why? Well we are very social creatures. As you know we are here to share and have fun, but this is just part of us; most of the time we want privacy. And to be able to say things and have it not be permanently reflected in our precious profiles always would be nice... remember your profile is everything in Steemit.
There is no way to communicate with other users in Steemit without making a public comment in someone's post, or posting and 
What about if you can message that person directly or even email that person? Just by visiting that person's profile you could get the option to send a nice private message, saying for example, "Listen, I just want to let you know that I did not like the post about fat people," or whatever you don't want to say in public by replying to his/her post.
Another sample I want to mention is that I saw this guy on Steemit that posted his PRIVATE key on the MEMO by mistake. I tried to tell him to change the password, but how can I do that when every post is public? So we exchanged a few posts and replies until I had to give him my email so the conversation could go private.
I don't know; maybe I'm asking for too much?
If you think this a good idea, please Upvote this. If you think it's a bad idea, Upvote anyway. :)