Did these "many people" ever look at the offerings of Khan academy? That's not academic stuff.
Kahn academy is early academic level at most, it is true. But it is good at what it does.
And Coursera lacks serious cohesion and supervision.
I'm not sure what you mean by that. Both Coursera and edX offer courses of a wide range of qualities. There are good to very good courses on both of them, there are very bland ones on both of them. Some of them even leave out the l and the n.
But university is about more than learning some formula by heart or reading a book. You need to get an understanding of the context of the theories, the process of discovery, and be guided through the history and current practices. It's not for everyone, but it's certainly not something an online course can provide.
Why not? Plenty of courses are close to identical to traditional courses taught at the university, going as far as using footage from those courses or even student discussions and exams. Good online courses provide lots of context, background, history, and development. I don't see what the problem is and why MOOCs would be inherently inferior in some way.