The original XDJ-R1 had a little bracket that mounted to the back of the device for an iPad or phone too, I used it at gigs to help search for tracks. Now standalone devices have good screens but that could be so useful for normal controllers and even mixers to help reduce the footprint in the booth.
I reckon the laptop stand and extra cables required are easily the most annoying part of taking a laptop to gigs, a one cable tablet solution would negate this.
I guess an 12,9" iPad Pro does that and if you dont want windows its a “cheap” option and might be sufficient for pros like yourself.
For being a real budget option you would take a normal iPad though and it would have more than enough processing power as well, thats what I meant. Also I think most professionals just prefer a standalone media player. less devices, less failures. And thats the one thing pioneer actually always did deliver on: pretty good reliability compared to any laptop/iPad solution.
For those it makes total sense.
With a modern laptop you can use 1 USB C for all as well. Im currently doing that using a hub for Ableton Link via LAN, Mixer soundcard and MIDI over USB control for 2 effects pedals. I guess it’s a matter of prefecence. I prefer to have a good hardware keyboard, so the tablet advantage is kinda gone for me…
What’s the benefit of having multiple screens? A Prime 4 like mixer with one screen and 2-4 LC6000 is a perfect DJ-gear setup for any professional Dance floor DJ in my opinion. Prime 4/XZ (A) or Live 2/RX3 (B) is good home/bar/dinner solution for most.
A prime 4 with a screen + 2 lc6000 awfully reminds me of a prime 4 
About the 2 screens: playing mostly back to back with the same guy, those 2 screens are incredibly handy! For browsing that is. But for just playing the track, you still want to see what is going on: BPM, loops, waveform, etc. Especially in 4 deck setups, it is not cool to look over to a mixer or laptop, or having to switch layer on another deck. We have 4 SC6000’s btw