Why would you want greasy fingerprints all over your display and gorilla arm syndrome when there's a perfectly fine keyboard and touchpad attached to the display for free?
No reason for gorilla-arm when touch is an alternative interaction mode and not a required one. You still have trackpad and keyboard. You can dynamically switch modes depending on the action.
Gorilla-arm was a fear based on the naive idea that if you had touch, you would be required to only use touch for every action.
mmmmm....grease
I don't actually want a MacBook at all, I was just joking.