Yeah, it seems to me like WotC originally wanted to focus on Greyhawk as part of their "back to the dungeon"/back to classic approach with 3rd, but they didn't know how to execute on it properly.
They gave us the gods in the 3E PH but not much more by way of setting. They did the cheap little gazetteer and used Greyhawk for the living campaign, but didn't give it a boxed set or a nice hardcover like FR got 1-2 years later.
Then the FRCS got a more deluxe treatment (perhaps aided by the fact that Ed Greenwood was still involved and interested in writing for it, though Sean K. Reynolds, Skip Williams and Rob Heinsoo also worked on it, so evidently a lot of the core team was behind it), and apparently a better reception. And in 4th they decided to try the new PoL/Nerath setting as default, while also supporting FR.
The 32 page gazetteer GH got reminds me a bit of the relatively short softcover splat books 3.0 originally had (Sword & Fist, Tome & Blood, Song and Silence, Masters of the Wild, and Defenders of the Faith). Which were functional and reasonably affordable, but I'm not sure gave as much depth as people wanted.