I honestly think this is one of the biggest things they need to change if you kill a rival the level/points go down they should go up increasing the the difficulty and what type (proto, military, fnix, apocalypse, etc.) spawn, because your an even greater threat then they (the robots) realize so they will throw higher leveled rivals at you.
Depends on how you see it, but maybe just lacks of definition by the devs.
The level and points go down, because by killing a rival the machines presence becomes less stronger in that region.
The threat is lower than.
But I know what you mean. This system needs a revamp in my eyes.