It really depends on the condition of the guitar. If you have a "mint" vintage guitar, then refretting it will devalue it, although if it is "mint" it wouldn't need a refret!
Generally originality is worth preserving. However, if the guitar has reasonable playing wear, which it will if the frets are shot, then I don't think a refret will devalue the guitar. It didn't leave the factory with unplayably worn frets, or say scratchy pots, so I would go ahead and get the guitar refretted. I wouldn't bother keeping the old frets either.
I've just purchased a 60s Gretsch needing a refret (which is good as Gretsch fretting is very variable to say the least), so I will definitely get it refretted to make it as playable as possible.