The two screen thing is simply to have each hand move away from the keyboard no more than they currently do. You’ll notice that most button heavy arrangers place the style control buttons VERY close to the left side, and the sound selection and Part selector buttons close to the right. Anything on a central touchscreen forces your hand to move MUCH further than is optimal….

Ideally, you want to be playing as much as possible, so doing much while you play from the touchscreen forces more time not playing. 30 years of refinement in arranger play layout shouldn’t just be tossed away, IMHO. Traditional layout systems took a long time to get where they are now. 🎹