I'm not sure I agree. If the course is interesting, I will sign up anyway, while still not completing it. That is, unless I can access the content without signing up, but that does not seem to be common.

I think the real problem is that MOOCs are not brick and mortar schools, and any attempts to mirror a brick and mortar school will only detract value from the offerings. I don't sign up to do homework or take tests, I sign up to learn something. I will then take what I learned and apply it to something practical in my own life. If successful, it proves to me that I understand the content well enough to accomplish what I set out to achieve. I don't feel the need to prove that to anyone else. A certificate of achievement hanging on my wall means nothing.

Of course, the real issue here is that the business model was based on the idea of selling graduates to interested industry partners. If I don't successfully complete the tests, I'm not valuable to them.