Has the product not been thin enough to easily hold one handed for years? We're talking about shaving millimeters off a 1.5 cm thick product. Not inches off something a foot thick
There's a difference between thin/light and holdability. My prior Asus[0] actually had a part sticking out the back (where the battery was attached) that provided an amazing grip. Flat macbooks, like my current Asus, I'm more afraid will slip out of my grip (or, held from the side, flex and damage something), especially pushing against it with the other hand while using the keyboard.
[0] https://www.asus.com/Laptops/U46E/