The new edition will be GURPS-based but not a GURPS supplement. It will be a standalone, completely self-contained RPG that happens to use GURPS as its "engine." Thus, it needs a combat system. Since we must fit in a setting, Disc-specific characters and items, and rules supporting the Disc's unique take on magic and such, there's only so much room for combat rules, so said combat system is simplified and optimized for the sort of fighting that's liable to happen on the Disc. Hope that helps!