Respectfully disagree. The pivot of a heel is not natural to me. But of course I doubt you have thumbs like me. I've got the biggest stubbiest hitch hiker thumbs you ever did see...
Many modern makers are utilizing a flat heel. The design with the recessed heel is round well enough and the pivot you speak of is achieved by well wresting the thumb on the sides...same effect.
I do understand your logic and it does make sense to a great degree, but I don't think the design we are shown in the photo is much different than what you speak of.
Lot's of modern designers aren't recessing the heel but are putting the heel flat on the sides of the guitar with a very slight rise...square and flat, I like that design to...But nobody can deny curves are beautiful
Heels look good. hahah no pun intended.