It will be great to have both the keyboard and the "monitor" side by side on the screen.
Hi and welcome to Arturia forums.
To me - Only if it's an individual option as it also can take to much workspace better used for other things.
I would like to able to use QWERTY keyboard with the standalone applications, so a keyboard in many is'nt needed. If one is a place without a keyboard, then it will help when on the SCR.
For a lot of reasons high resolution screens still is'nt to good for music production as many applications get to small. Even when using normal Full HD 1920x1080 pixels many applications is very small, but i would say this is a standard resolution today on PC's. Also many still use screens down to at least 1366x768 pixels. Actually Arturias applications lowest resolution can be to big - especially in some DAWs using a 1366x768 screen. The bottom panel vanish, and thats also why it's a bad place to have displays and anything else. Arturia have'nt taking the DAW's plugin window size into account.