It's actually not a retarded system I feel, it allows for you accidentally clipping someone during a fire fight and it does a tiny percentage of damage.
Instant rogue would be idiotic, as its been mentioned, plenty of people run in your line of fire, deliberate or otherwise, it can be tricky to stop in time.
Problem is it seems based on your damage vs their defense. I have shot people with 1 bullet by accident and been classed as rouge simply because they walked in front of my line of fire. It needs to be really well balanced and i think it will be extremely hard to pull off sadly.