iPhones are iPads have a milled CNC “unibody” as well… Being able to dictate where to have more thickness helps a ton on the luxury feel. Most of the chips are recycled anyway into new billets.

Unibody is a very appropriate technique for a small portable device that needs to be strong from force in many directions. It is overkill for a keyboard.

Overkill is the point. Same thing for iPads and iPhones. It gives a luxury feeling. That and Chinese manufacturing have made milling a very cost effective manufacturing method.