Thing is..we don't really need them so much anymore, at least the first part. I guess you could easily say that movies and TV have certain aspects that teach people something in some way. It's just that so little of them do anymore that technically, we have no modern myths on those fronts. It's all for pure entertainment. Not that I mind it because to be taught a lesson everytime a i watched a movie would get a little bit repetative I guess.
It kinda sucks that we will have so very few "moder myths" to pass on to history unlike the Greeks or Romans. No one is gonna remember this period in history for it's myths anyways. It'll all be about terrorism, war, Bush and general unrest in the world.
EDIT: YIYF is completely right tho....if much gets remembered, I think Star Wars will be the ultimate Good Vs. Evil myth of our time.