In the early sixties (Freewheelin') Dylan used the expression 'bare naked'; this obviously meant a bit more than just 'naked'. Maybe the more general use of 'bare' as an intensifier owes something to that.
(This may seem a bit far-fetched, but similar (ish) extensions of meaning take place regularly as a language develops. To cite one example from Vulgar Latin, it used the ablative mente (with a ... mind) to make an adverb regularly from an adjective, rather than operate the Classical Latin rule (not simple, applying differently to different declensions, with lots of exceptions). This worked fine with adjectives like placida: placida mente -> with a placid mind -> placidly. But the same trick - applying the suffix -mente to any adjective - has given most if not all Romance languages an adverb form ending with -ment(e)) - meaningful originally, but having become what linguists call 'a productive mechanism' in any verbal context, no matter how irrelevant to the original meaning).