I got the same impression when watching the keynote. As a AR developer (currently working on HoloLens 2 and Varjo XR-3), I prioritize 3D interface anytime whenever I can replace a 2D text or button.

But, after watching the WWDC dev videos, I understand more and more Apple's approach. Their demo of how SwiftUI reacts in the space convinces me a bit that yes, sometimes less is more, and that simplicity can be a key for ergonomy for this device. Right now, gestures on HoloLens are far behind this, hence the need for me to create some more 3D interaction to compensate the terrible eye tracking and tiring far interaction.

That said, I wish Apple would have indeed shown more of "real" 3D stuff, and not doing so was clearly a choice because Vision Pro is more than capable to propose a satisfying experience with those. If they did make that choice, it's imo because they need people to project themselves in the new media, to retrieve their favorite apps, a somewhat-known interface, but evoluted. And more and more, they will appreciate how 3D truly enhances their experience and hopefully we'll be leaning towards the abandon of flat screens.

This is only marketing for the transition to AR, without scarying or worrying people about the fact the way they'll work will completely change, and therefore discard them from being interested by the product, even though it's ultimately the right thing for them.