How do you conclude that replicants don't appear to age? Most of them didn't live long enough to appear older, but for those that don't have an expiration date (presumably Deckard and Rachael) , there was nothing to imply that they wouldn't appear to age as they, well, aged. Apparently quite a few people did not understand what a "replicant" was supposed to be in the movie, or, for instance, why they would need human organs, like eyes. Hint: NOT A ROBOT.