"Cut from the original master tapes"

this is a phrase I see often when looking at new vinyl of old recordings. I always wonder if this is a good thing. I'm sure the tapes used are of a better quality than the 8 track, casette, or reel to reel tapes that I used but were they really of a quality that they would still be Quality today? Do they not lose their muster, so to speak, like everything that one deems to be from that period of time referred to as "In the day" (yours truly included)?