Most glider pilots I know would be more then happy to get a R/T licence, the main thing that stops them is that they have to learn so much that just isn't needed for them.
Ideally it would be great to have a seperate R/T licence for glider pilots that will focus on what they need, making it mandatory would be even better. Problem then of course is that gliders then have to all carry radios that cost money, and they have to be powered etc etc.