I think there is some merit to the age thing, but even if we were only 5, 10, 15, 20 years old when we first saw Star Wars, that movie(s) was pretty revolutionary. I'd say you have to place them (4-6) in time as classics, maybe not in the same way as a flick like Gone with the wind, but in some fashion I'd say its amoung those.

Thus why not expect the prequels to be quality movies. They just don't come close to that. Either Lucas is pulling the biggest Hollywood prank ever and making these suck or he's just lost any talent he ever had.