I disagree to an extent. For some classes (it's quite variable), the forums can be of great quality, and it can be greatly enriching to be learning the material (and educational tangents that occur in the forums) along with lots of others. It's just not possible to get a cohort of people learning things at the same time as you on your own.

In fact, I am kind of hoping that a community is made where people can get together and study any educational material themselves. Coursera still lacks upper-level classes; it would be great to use the great aggregation of the internet to find a group of people to study advanced material together.