Good beginner content is a big problem, I agree that recommending a stream of content with ~5% unknown words would be very cool. On the other hand, being a small indie developer, maybe it's better that I concentrate the smaller niche of advanced learners since I'm then not directly competing with Duolingo and other highly funded sites.
I would like Readlang to be more social, but haven't got around to it yet. I thought about adding disqus comments as a quick solution but they aren't ideal, requiring you to log in a second time.
It's probably more sensible for me to polish and optimise the current feature set first before adding social features.