I work as an assistant teacher every now and then and it is mostly small group teaching and going over the homework exercises. What I have seen is that the first couple of sessions are totally worthless subject wise. But they are extremely critical. During those sessions the students learn to know each other and me. When everyone is comfortable attending the sessions can the actually learning begin.
From this perspective I think MOOCs would need the following. Firstly, you need to create small enough groups of people that are comfortable discussing the subject with each other. Encouraging local study groups is a one way of doing this. The other thing is to encourage discussion through anonymity with forums or IRC. And you need to acknowledge that you don't reach all of your students with these methods and not rely on them too much.
> I personally like to learn in isolation, I have a tendency to quickly ~plagiarize ideas of others thinking I understand, so learning alone in my room is better.
There's nothing wrong with self-study per se, but it has a one great flaw. It is easy do the kind of plagiarization I think you are talking about without knowing. This can be remedied by getting feedback from an instructor, or going through the material with someone else and then cross checking how you understood the ideas.