Lovely post Robin.
I think you hit on a significant issue here – with all of the potentials that online learning brings, the formal course development and validation processes may be restricting new approaches to assessment.
So there is a temptation to take the traditional teaching approaches and make online learning activities mirror these rather than thinking in new ways about learning and assessment. So a good example is the way many online courses still adopt the lecture approach with talking head videos. I’m not saying these are not valid for many subjects. I think it is difficult for teachers who have to work within institutional constraints or within the confines of their subject’s traditional approaches to try new things. Being innovative means taking risks – and this may mean risking learner experiences or achievement.
But there are some great examples of collaborative and open courses that are accredited formal courses. see the US course http://ds106.us/ and the UK open media courses at Coventry University http://comc.loumcgill.co.uk/