CPU + battery in the top-cover kills the balance of the laptop and makes the whole thing heavier. It's a really awkward design compared to a clamshell laptop with a very thin display-only lid.

Flip-around convertible or kickstand with soft-cover keyboard both work a lot better, but also both have trade-offs.

I somewhat fondly recall my old HP Windows Pen PC where the screen would twist and lay back down over the keyboard. That thing was a brick, but it had the correct balance for a laptop and the keyboard keys were out of the way in tablet mode. Maybe Apple will bring that form factor back, but with a super thin OLED display and a really lightweight device.

With the surface books, the bigger battery and graphics card in the base ensured that it was the heavier part.