The current UI is not touch friendly at all with tiny on screen elements and no support for multi touch either. My new backup PC is a 10 inch tablet which otherwise runs Cross DJ perfectly well (an HP Pro 610 G1 with Atom Z3795 CPU , 4Gb RAM, Windows 10).
(multi) touch is a matter off adding a "touch layer" to the software. Whereas by default you have "cursor" input with this layer multi input is possible. So just another input method (also keyboard and mouse).
Never had to work with this, so can't tell if it is easy to implement for multi OS.
Personally, I like the layout and dark look of Cross. I think if anything needs to be improved it might be waveform scrolling to make it smoother, but the UI itself is intuitive and easy to understand. Drastic changes in work flow will put people off, and I for one, certainly wouldn't want a brighter interface, as I prefer to not have my face "glowing" in the DJ booth... LOL