Just to throw my hat (opinion) into the ring...

I've tried pretty much all of the "MOOC's" out there, and so far the only two I've stuck with were Codecademy and Udacity. Why? Precisely for the reasons that are mentioned at the article which started this discussion. The format of Edx and Coursera is just all wrong for most people who DO want to learn something but have a busy life that is not conducive to a traditional college class.

Besides which, all too often, Coursera and Edx just throw a college class online (lectures, course notes, homeworks, quizzes, and tests) and call it a day. Then they have arbitrary deadlines--which I acknowledge might help some people but the first time I got a deadline email I decided that it wasn't for me...no matter how interested I was in the class topic. I'm already married and a father who is working part-time while doing a Master's program in Computer Science. So I don't have huge chunks of time available for traditional course work (in addition to my Master's coursework). I have little bits of time every day which I use effectively to progress through the Codecademy and Udacity coursework. Slowly but steadily I'm getting through both and making substantial progress.

But, since Coursera and Edx require huge blocks of time committed every week, and a tight timeline to complete the course, I just don't find it's workable. Which is sad since they seem to offer some tremendous material.

In short, I think that Coursera and Edx (and probably colleges in general) should learn a thing or two from the highly modularized approach of Udacity and Codecademy.

I find that my learning retention and interest remains much higher with both Udacity and Codecademy because they present a little material (little bite-size chunks) which slowly build into more and more challenging material and intersperse "challenges" or "quizzes" throughout--rather than the traditional approach which--by necessity--was far less responsive.

The fact is that online learning doesn't just reach potentially numerous people that wouldn't have otherwise been exposed to such educational opportunities at such a low price (currently free), it potentially allows for a radical rethinking of the traditional education model.

I think that it is sheer ignorance to say, as some have in the comments I've read (and as--apparently--Coursera maintains), that those who don't finish a course just aren't interested enough or motivated enough. This is ridiculous. The very same (allegedly "unmotivated" or "undisciplined" or "uninterested") people may be successfully working their way through Codecademy or Udacity. And yes, it may take them a while, but eventually they'll complete a Codecademy "track" or a Udacity course. And they'll do it one bite-size chunk at a time...and sometimes, say on a weekend, they'll plow through a whole bunch of bite-sized chunks.

When Coursera and Edx adopt a more bite-sized format which isn't oriented around arbitrary deadlines, I'll check them out again. Until then I'll stick with Codeacademy and Udacity.

Bottom-line: the standard model is broken. Lectures and homeworks and quizzes and tests are poor ways to educate. For many years they were the best we could do within the technological constraints we faced. But now we can do better. Heck, I'd encourage everyone working the bleeding edge of online education to think "outside the box" and try new approaches. While the best new approaches I've seen have been those utilized by Udacity and Codecademy, that's not to say that there aren't even better methods--methods better at retaining learners (keeping learners engaged), AND methods which excel at increasing retention of material.