The choice of Greyhawk is nostalgia bait for older fans and IP implantation for new fans.
Strixhaven, Eberron, or Nentir Vale are strictly better choices for an introductory setting and teaching material for a setting.
Probably. And yet, those more recent books, especially the ones that have presentation and content that's overtly marketed for "the kids" the last few years, like Ravnica, Strixhaven, Radiant Citadel, etc. haven't sold as well (according to data I saw on Professor Dungeonmaster's YouTube channel anyway).
Is almost as if someone at WotC has enough sense to suggest that they not go full Kathleen Kennedy or Kevin Feige and alienate their legacy fans to chase an elusive sexy young fanbase that maybe generates buzz on X or TikTok, but who doesn't seem to spend all that much money.
Instead we're getting... a swan song adventure about Vecna that's about as classic as you can get, and Greyhawk is back as the default setting. Sure looks to me like WotC is deliberately marketing to older fans as well and signaling that this game isn't just Furries & Feelings for the kids. Forget about the last couple of years of books, guys, seriously.
D&D seems to go through this cycle periodically. They drift too far from the core audience, start hemorrhaging fans, and then return to classic tropes mingled with a bit of new stuff to reel them back in. Most recently with the launch of 5e a number of years ago, but it seems about time for the cycle to repeat. Especially after the last couple of years worth of relatively (relatively, mind. I'm not suggesting that these were all flops) poorly received products and PR gaffes.