This idea of a certificate/permit/licence to go into the woods is a terrible idea in every conceivable way for reasons already mentioned in this thread and probably more besides.
Cost, exclusion, meddling in something that's about getting AWAY from that sort of thing, ratcheting, regulation and more besides.
The more the "authority" gets involved in things (with a tiny number of exceptions) the worse things become.
I'd sooner be prevented from using some land than need a licence to use any - and while this isn't proposed by the OP as a licence like cars but a cycling proficiency test style certificate... the words "thin", "end" and "wedge" spring to mind.
If such a scheme existed, people like myself who don't have a great deal of money and are really attracted to wild camping/bushcraft, in part do to its lack of cost, would be priced out. If such a scheme were available I could see landowners who otherwise take a more sensible approach deciding that it'd save a certain degree of headaches to only allow certificate holders on - meaning those who either can't afford or don't want such a certificate simply can't follow their passion any more.
Bad idea.