Namcha
It cannot be fully realistic, but the goal is to encourage players to behave more according to their faction. Maybe the 100% will be harder to keep. But to pretend to 100%, shouldn't you be totally devoted to your faction without any fault ?
Okay, maybe a rework of the pvp point scoring could be more punitive against mortal enemies teaming up, currently opposing fames on the same team cancel each other out, but unfortunately that was not what this post was about- although in spirit it wants more clear cut faction divisions, that could be done by modifying the already existing rewards.