I'm still on 2.7. That does look very inconvenient, I am not looking forward to updating...
Just a guess, with more Prusa Connect integrations, maybe they're making the framework for the web UI if they do offer a cloud-based Prusa Slicer option as Josef teased on Twitter, sort of iterating on your point about them trying to "keep up" with the ecosystems competition has created.
The only appeal I would see is making the software feel less intimidating for beginners perhaps? If that's the case, it would have been nice if they built on the "Simple", "Advanced", and "Expert" tier system, and had the menu hidden for the "Simple" mode but fully visible for the "Expert" mode.