I wouldn't call Delcam and KUKA|prc "competitive software" - with Delcam you can do milling etc., while you can use KUKA|prc to do nearly anything - take a look what e.g. Artis Engineering is doing in Berlin: https://vimeo.com/user12374666
So for milling it definitely makes sense to use specialized software like Delcam, MasterCAM/RobotMaster, etc.!
You can of course still do milling with KUKA|prc quite nicely, either by programming your toolpath-strategies yourself or by importing G-Code, e.g. from SprutCAM. We recently added a functionality to output positions in a format that can be read by KUKA CAM.Rob for very large filesizes.
So to sum it all up:
Delcam = specialized milling software
KUKA|prc = general parametric robot control software (but can also do milling)
All the best,
Johannes @ Robots in Architecture