You all are forgetting the cost to an arranger of adding buttons for every function that can easily be done with a touch screen. Take the Abacus, for instance... Absolutely bristling with buttons and sliders.
Absolutely too expensive as well (and a large part of that expense is the physical controllers).
Touch screens offer a way for the manufacturer to include FAR more live control than could be afforded to us at the same price if all these functions HAD to have physical buttons. Personally, I find absolutely ZERO problems with operating my Roland with the touch screen. OK, with one exception, I WOULD have preferred a different location for a couple of the screen buttons... But I would be happy for them to merely have the location changed, rather than have them changed to physical buttons.
At least, with a touch screen, there exists the POSSIBILITY of the manufacturer changing the layout with an upgrade, but a physical button in the wrong place (and we have ALL bitched about that one!) cannot be corrected without buying another model.
And sorry, but reports of bad buttons outnumber bad touch screen reports hundreds (probably tens of thousands, in real figures) to one... I've been stabbing at mine in the heat of playing for over three years. Not a HINT of a problem. My Triton (original one) is STILL working fine, I know guys who have used them six gigs a week for as long as they have been out, in outdoor, seaside venues. No problems.
A bad button layout is just as hard to overcome as a bad screen layout and slow response (which has completely gone, nowadays). You can keep sticking to older systems as long as they keep providing them, but operational ease will suffer, or the price will go up, as manufacturers chose between buttons or no control at all.
BTW, Roland have a neat system where, if you press and HOLD any physical button, the edit page for that function pops up on the screen. VERY fast, very intuitive. Others should copy...