Make it like getting a pilot's license
While the aviation community is safer and upgrades and currencies and check rides are common could you see the infrastructure that would take for bikes? getting your 6 month check ride, 20 hours - check ride, don't fly for 30 days - check ride, so on so forth. So yeah, it'd be expensive. I think if there was a correlation between taking upgrade courses and a noticeble differene on your insurance rates, THAT would entice people to do it.
As for 300/year insurance, I've seen some horrific crashes (other than this months one in fergus) where the pilot walked away compared to some slow speed crashes on bike where the guy is messed up pretty bad... And riding in 2D vs flying in 3D? I think flying is easier until it all goes to **** and suddenly becomes harder than riding very very quickly.