I'm sorry if this sounds negative, and I guess it is in some parts, but I sort of feel that tabletop gaming has focused on the decades-long players it already has at the expense of appealing to younger generations. There's nothing wrong with that, but it doesn't gel well with the supposed unifying aspect of 5th Edition and recent talks about increasing diversity and representation in geek culture (lso something promoted by Wizards, Onyx Path, and the big dogs in the industry).
As one of those decades-long players . . . I think you are right, but I think you are missing some cause and effect elements.
As I've seen it, a lot, if not most, of the drive with settings and "feel" has come from the "squeaky wheels" - whichever sub-group of fans makes the most noise gets the most lip service.
And currently, that seems to be the self-proclaimed OSR crowd, particularly the Appendix N fanbois.
That has two major problems:
1. Just because they are the noisiest, including the most active on forums or social media, in no way establishes they represent what is, or should be, the core fan base. The biggest case studies of this are WotC trying to go "Iron Kingdoms" with their last version of the game, and even keeping the writer of that around for the current edition, along with the echo chamber that is Paizo and its wallowing in spellcaster indulgement and torture pr0n adventures.
2. Particularly with the Appendix N fanbois, most of them are utterly clueless about the genre they are insisting is the "heart" of D&D. I've actually read massive amounts of Appendix N, and while it is great inspiration on a trope level, direct conversion of the material would be a complete disaster. To begin with, 90% of the stories are solo adventures, with 9% being duos, and only 1% getting into anything even vaguely resembling stable teams. Mind you, some people love campaigns where the PCs spend more time backstabbing each other than fighting any monsters, but that is definitely not the dominant market, no matter how many OSR clone games they Kickstart.
On top of that is just how jerky vocal grognards tend to be with new material. They will whine about getting more material for their favorite setting, then almost invariably trash it to the point of driving away newcomers from even considering it. Of course as soon as they've killed it they will be out in force to pick up "free" copies of everything for use in their campaigns, blithely dismissing reminders of how they smeared it so viciously when it was being issued.
So as much as I'd "love" to see a dozen new Greyhawk sourcebooks, with me as project manager of course, realistically I recognize that WotC should move onto an entirely new setting, preferably one that resonates more with new fantasy trends (without subordinating the system in the process) to attract new players.