While I never used a hotas, I can say a controller is leagues above a keyboard and mouse, for me at least.
Also the xbox is a fixed spec machine, well above minimum specs, which I'm sure more than a few pc players skirt by. I'm sure the avg xbox player won't be at any disadvantage compared to an avg pc player, if crossplay was allowed.
The reason specified for lack of crossplay was, different patch times. Which makes sense, but is still disappointing.
I am pretty sure that the Xbox One can at least run the game on either High or whatever this game's version of Ultra is.