Contrary as it may sound, another downfall of online education is that it isn't actually as instant as face-to-face to communication. Online discussions can never be as dynamic as a good classroom discussion. Emotions and passion are more difficult to detect. The first post suggests it is easier for some students to be "vocal" and honest online. I've found that more often than not, these types of students (and answers) are in the minority. Online discussion, in my experience, tends to be more bland, more rote, and often repetitive.
I will never be a proponent of replacing face-to-face anything with technology.
On a positive side, however, I do believe there are many classes/subjects which are, in themselves, not subject to a lot of discussion, opinion, nor emotion. These subjects make very good candidates for the convenience of online study.