Just because the origin of a celebration may be mythic or legendary, I don't see why I should try and write it out of social history, or my present culture. There's good bits in the Christ story, and it's a great excuse for some mass family gatherings, and general giving and goodwill. As long as you don't tell me I'm going to hell, I'm not going to start pulling out archaeological and historical evidence on you. Let's smile at each other, wish each other well, and have a good time.
I don't think that reverance or respect for the dead needs the dead to be hidden from sight completely. It is the attitude that you bring, as a witness to a dead body, that matters, not the display and witnessing of a dead body, per se.