from one point...going thinner everywhere makes the device too fragile
Well there have been rumors of a "foldable" iPad.
I do usually carry my M1 iPad Pro 12.9" inserted into a folio, or Apple Keyboard Case. I'm not sure how safe that is? But popping the new iPad in and out a fully framed case might be a bit dangerous. For instance my Zugu Case requires a good bit of force to insert or extract. The Logitech Combo requires less force, but I still try to be as careful as I can.
Apple's magnetic folio and keyboard mounting system requires no mounting our extraction force at all. But I'm not a fan for several reasons.
I do occasionally carry my mirrorless camera and lenses in camera bags. While they have thinly padded compartments for tablets or laptops, I think I'd be worried about the safety of the newer, thinner iPad fending off damage from the camera equipment.
I wonder how well AppleCare+ will be honored for bent/cracked new iPads? Time will tell.