I'm not going to defend that kind of approach to radio - particularly not taxpayer funded radio which has the potential to have far more breadth and depth in its content than commercial radio - and I suspect it is a relatively new innovation, inflicted by the current clueless management at CBC.
Like many Canadians I still mourn the loss of the amazing Brave New Waves (http://en.wikipedia.org/wiki/Brave_New_Waves), and there's no way that all or even most of the obscura that was being played on that show was in some giant pre-licensed library of music. I suppose that cancelling one-of-a-kind shows like that is an aid to 'getting greater efficiencies out of the content management pipeline' or some such nonsense.
But yes, things were much simpler then. The demise of BNW seems to have coincided with the transition to satellite / podcasts / streaming for the CBC, at which point I can only assume that navigating licensing issues got a great deal more difficult. Even the single archival clip of BNW that CBC offers for streaming, from 1984, bears the notice Due to copyright issues, there are no songs in this clip.. That's just dismal.
Most CC artists would be thrilled to be used on the CBC and would probably charge very little for that usage. They just won't want it on a Budweiser Superbowl commercial without their knowledge, consent or compensation. Or at least that's my view on commercial usage of my work.