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GnomeWorks
Thankfully, not every young person is as close-minded as you, uninterested in anything old simply because it is old.
I would say the age of 18 is the latest I would expect an intelligent person to have gotten over the idea that art progresses in a technological fashion, like cell phones and computer hardware.
It's especially sad that the frequency at which Vance is mentioned in 5e discussions has, rather than piqued your curiousity, fortified your resolve to never read him, because I suspect that you would find his stories "The Last Castle", "The Moon Moth" and "The Dragon Masters" to be surprisingly fresh, particularly if you're a fan of sci-fantasy anime. Of course your unfamiliarity with his work is not any sort of indictment on his present visibility if you don't read ANYTHING, which somehow I suspect is true.
But the worst thing about your post is just how wrong it is about what mainstream fantasy is like today. I'll give you the benefit of the doubt that you're not being disingenuous, but no, you do not in any way speak for the entire current generation of fantasy fans. I honestly don't think that your preferences are even very representative.
Anime does not have mainstream popularity. Where does this idea even come from? There are no mainstream anime feature films. Cowboy Bebop is not bigger than Conan. Conan had another major film adaptation last year, and there was the John Carter of Mars film this year (an even older pulp fantasy character). Lord of the Rings obviously is still enormously popular, with The Hobbit coming out soon. HBO's Game of Thrones series is huge. What are the recent successful fantasy videogames? Skyrim, Dragon Age. Both very similar to classic D&D in feel. Todd Howard from Bethesda Softworks and the Doctors from BioWare have both spoken about their love of D&D and the influence its had on their games on many occasions.
D&D clearly could hit any reasonable sales goal while being very traditional in its fantasy inspirations. The pool of people who are into this is big enough. In fact it's far bigger than D&D could ever hope to tap. D&D does not need to reach out to other groups (note that I'm not necessarily saying it shouldn't, what I am saying right now is that the idea that it
needs to is like swimming in a lake and wishing it were an ocean).
Your personal (superficial, since you haven't actually looked into it) distaste for D&D's fantasy roots does not have any more bearing on what 5e should do than anyone else's preferences.