The problem is that it is too easy to accidentally touch. Even if you set it to the Fn keys, a slightless faint of electrical conductivity between a side of your finger and the touchbar while you are pressing a number suffices for a key press. With a real key, you actually have to properly press the key. That might happen by accident, but is definetely harder.
Yes. It's the moments when you're carefully editing something really important... precisely pasting some line into a new location... you double and triple checked that everything is right.... and then BOOM your window is gone and replaced by some other app, or a control panel or... some weird thing happens and you're not sure what.
