GUI - internal code / HAL connect

I don't see how it's very different safety wise -ie it's not realtime.

I just find it more likely to misclick or mistouch on a screen than hitting the wrong physical button on a panel. Also this way I can have different haptics for different types of commands (ie 'machine enable' can be a larger button with more travel than a 'zero axis X') while in a gui a left button mouse click feels the same whether I clear the backplot or start a program. Also with physical buttons I can jog 3 axes without ever taking my eyes of the machine just because I can have fingers on more than one button at the same time.

From a machine manufacturer point of view I certainly get the point of installing one touchscreen and doing all the interfacing through a GUI.

I meant the gui code can export all the Halpins that halui does.

Ah, I see. I have not thought of it that way around. Instead of having the gui sending commands through hal pins to halui, as I was thinking before, we would send the signals that now go to halui to the gui instead. 
Either way, I'm starting to see now why there might be advantages to have either halui OR the gui to be in control rather than have signals coming from both in parallel.