But not everyone likes "generic". A generic setting is not "for anyone". Which is why we need settings like Ravenloft, Planescape and Spelljammer.
But, there are some significant advantages to generic - namely that it can be repurposed so much more easily than more specific material. I can plonk down pretty much any of the Sword Coast 5e AP's, with little or no revision, into virtually any setting, pretty easily. Never minding specific bits that can be repurposed. Trying to tie in Planescape material, for example, gets a whole lot harder. Or Darksun stuff or even Ravenloft stuff.
The more specific the setting, the harder it is for people to repurpose, AND, the less likely that someone will make the attempt as well. I know, from experience, that if I pick up something for Forgotten Realms, be it mechanical or lore, I can pretty easily use it in another setting. But, I also know that I'm going to have to hunt and peck a lot more if I pick up a, say, Planescape, supplement. So, given two books, I'm going to pick the Forgotten Realms one first every time.
And I think this is how it generally works for a lot of people. The more esoteric and unique the material something is, the harder it is to actually use at the table and the less likely people are to pick it up on a whim.
But, rolling back around to golden era of lore - again, I cannot fathom how this isn't the absolute golden era. You have ACCESS to all that lore of yesteryear. When I was gaming in the 80's and 90's and even the ought's, you just didn't have access to any of this material unless you went out and bought it. Which meant the lore for any game was going to have great gaping holes in it unless I started obsessively buying material. Heck, this was the primary reason I never, EVER bought into any of the TSR settings at the time. Other than a handful of supplements (Faiths and Avatars being a good example from 2e), I never bought any TSR setting books. None. Had zero interest because I knew that if I wanted to actually use any of it, I'd have to buy fifteen different books and then try to cross reference it all. By the time I was done all that work, I might as well just write it myself.
To me, the fact that all this material is now available, easily, easily searched, makes it fantastic. I mean, I was doing a bit of background research for my Shining Citadel adventure (based on the idea that in the center of the Shadowfell there is a shining castle where all the light of the plane is housed) and I came across a reference to The Blinding Tower (possibly the same location with a different name) - from the Planar Handbook (p 162). There is zero chance I would have been able to find that information in the past. None. I would never have bought that book, nor would I even consider looking in it if I had. I certainly would never have made the connection.
But, now, because of things like wikis, all that work is done for me and I have a possible extra bit I can add to my adventure if I want.
How is this not the golden age of setting lore?