The only thing that would make sense at this point is if repairing your own gear also gave it some minor enhancements and randomly endowed it with permanent enhancements. Maybe increase those odds by letting your equipment get really low before applying Dark Matter.
Otherwise we'd still be using the NPC 99% of the time even if everyone could repair anything with the requisite Dark Matter.
Besides...this is Dark Matter, shouldn't it do more than just repair? C'mon...
