One of my pet theories is that the 'vintage era' guitars were mostly made with old growth timber. These days, unless you're dealing with extremely specialist woods (like ash that's sat under a swamp for centuries), that's just not the case.
Funnily enough, that has come up in the history of replicating the Stradivarius. One theory I remember was that there was a mold or fungus in the wood he used that trees don't have anymore.
