Debate fuels my Fire
Hm. This didn't really answer my question, being what you thought specifically about the content centered around Keoland and the town of Saltmarsh.It was fine. To begin with, the original U Series (Saltmarsh) wasn't exactly heavy Greyhawk! But it neither particularly offended, nor made me stand up and go, "A ha! They have it! That's it!" Probably because the material could be easily transposed into any campaign setting (how much work would it take to use that material in a FR setting?).
On the second point, I think that most of the peripheral debates about Greyhawk are usually red herrings for the real issue. It's not (in my mind) really about Tieflings and Dragonborn and whatever.
It's a debate between those who want to have Greyhawk released in some way that respects the integrity of the setting, and those who just see it as a grabbag of names and things to use for 5e. It would not be overly difficult to have an amazing new Greyhawk that has the capacity to include "Tieflings" (modded as fiendish and Iuz) and Dragonborn (exotic seafarers from the blank parts of the map, perhaps?). Who knows?
But I would hate for them to just release a Greyhawk as another default, kitchen sink setting.
I'm sensing a bit of a problem here, in that a lot of Greyhawk players don't want Greyhawk to be super-filled in, detailing nearly as much information as FR does because they want more of a sandbox that DMs can fill themselves.
However, if you make Greyhawk too vague, it seems more like a kitchen sink (using your words) that can be planted in any "generic default fantasy."
I thought Ghosts of Saltmarsh struck that balance quite well, feeling tonally distinct from FR and more of a rugged, frontier setting. But you took it as still too generic.
So yeah, not really sure what release is going to make most Greyhawk fans happy. I'm starting to think it is better to just steamroll over GH fans complaints as their too contradictory, and just make a book with the style (editing/format of book, not the tone/material) of Eberron: the Last War.