I have used the NUCs to integrate controllers into small robotic platforms and custom lab equipment. They are a good 'it just works' platform that you can scale

I have used the NUCs to integrate controllers into small robotic platforms and custom lab equipment. They are a good 'it just works' platform that you can scale performance v cost over time as needs vary (need image processing? drop in a core i7. just motion control? save money and go with an i3 or atom). Also they are more reliable and performant than RPi, and relative to the cost of the motion control systems, the NUC is a rounding error. Notably the NUC has a standardized base plate mount that requires only two screws, and it has nice rubberized stand offs that isolate vibration. So, mechanical integration is super easy, and swapping out a NUC in the field is also very fast. In some cases it is easier to do a firmware upgrade by switching out the whole NUC than trying to walk a lab tech through punching a hole in the corporate firewall, or running an ethernet cord through the production floor, etc etc.