The Touchscreen Commander is an option so the boat can be purchased with ot without. All depends on how the OE spec'd it out.
The touchscreen has a bit more information available. Water temperature comes to mind. Or was it Air? One or the other is not available on the non-touch display, I forget which one. It will also give you a map of the water depth instead of just a number. And you have a Garmin map available. The other advantage is having access to multiple information at once. For instance, you can not view your compass harding (bearing) if you are in cruise mode.
How important these are is up to you, but there is not much, if anything you cannot do with the regular screen.
My first Scarab did not have the touch screen but my current one does. While I don't regret having it, I kind of regret paying what I did for it. It looks really nice, but I just don't feel it's worth what it costs. To be fair, I didn't really think it would be, but it looks really nice.
One thing I did like is that it removes the selection controls from arm rests. I always found them to be annoying there. Scarab originally had them on the front console but moved them, for some reason, to the arm rest. I'm not sure when, but 2017 might be pre-move.