The sides can be made grippier and the back of the phone left slippery, so the in-out of pocket experience is nice, while the grippier parts fit in the palm when in use.
The added thickness on the border is also a welcome affordance, and as your fingertips are on the thinner back it feels thin still.
That's fair. The corresponding full-body case Apple is releasing for $49 does have a conspicious extra lip higher than the camera bulge (albeit that's typical to mitigate camera flash glare). https://www.apple.com/shop/product/MGH24LL/A/iphone-air-case...