IMO, the works of Bach, Beethoven, Mozart, etc. stay fresher because they are constantly reinterpreted by conductors and musicians. Just look the debates aficionados have about the merits of many recorded versions of the same symphonies.
The Beatles' music, on the other hand, is primarily heard the same way every time as performed and recorded by the lads,(not counting interpretations used in commercials). I can understand how someone might be burned out by over saturation.