I think the BBC are scared of appearing to go back to the Open University days where the programme was just a lecture - often given by people with poor dress sense and no apparent charisma.
However they have gone too far in the other direction. I think this is just a reflection of the general dumbing down of the British education system - modern education is just interested in league tables rather than nuturing wonder at the world around us. The result is a generation who seemingly struggle to grasp complicated subjects - presumably because they haven't been given the tools to do so by "the system".
I don't suppose the prevalence of arts graduates in the establishment is helping either.