Considering the comments on this site that the Mike Harding show gets regarding the artists he plays on his radio programme, do you think a TV show would be any different? After three weeks we'd all be moaning that our fave folkies weren't getting any airtime and that Kate, Eliza, Martin, Sean, Show of Hands, etc were on every week.
Anyway, people who make TV programmes have no idea that folk music exists. How many times have you watched a documentary and thought "I know a cracking song that would fit there"

Gary Aspey used to tell people that they'd been offered TV shows but he'd turned them down. It uses the act up and if people had watched the programme they wouldn't get out of the hose and come to the live gigs.

Cheers
Mark