[ . . .] as a society, we share fewer stories, myths, and other core information [. . . ]
This is true. We are in a maze of twisty little subcultures, all different. We have more choices (and more diversity) than ever before. I consider more choice to be a good thing, but it also means that the more choices there are, the less likely that two people will make the same choices, and we will find less overlap between people's experiences.
My parents' generation had certain choices of music to listen to. But most of that music is still available to me today. I can choose from all of their music, plus all of the music created since then. The same thing goes for movies, books, etc. Although some things do go out of print, in general the choices keep growing.
This reminds me of the difference between today and the Golden Age of video gaming. In the Golden Age, there were not very many games to choose from, so everyone had played most of the same ones. Gamers had a lot of "shared experience" because everyone had played Asteroids, Missile Command, Frogger, Pac Man, and other classic games. Today, we have a lot more choices, so the gaming culture is more fragmented. The gamer who follows the Final Fantasy series may not have much to talk about with the person who has played every Tekken game, and they both might share awkward silences with the gamer who loves the Madden football games or Tiger Woods Golf. Not only that, but now there are PC gamers, Xbox gamers, PS2 gamers, PS1 gamers, Gamecube gamers, Gameboy Advance gamers, and many more varieties.
More choices create cultural fragmentation. But I'm not sure that's a bad thing. There are fewer shared experiences, but there are more fun experiences to choose from. I guess I don't mind being in a maze of twisty little passages, all different, as long as I'm having fun.