Instead of just wanted why not bring back the Elite Offender and Fugitive ratings. Things like smuggling and colliding with stuff gets you a offender rating where only security will be allowed to attack you if there are no Fugitives in the local area, however killing innocents will net you a Fugitive rating where everyone can kill you.
This might stop the massed killing for 400Cr bounties and would mean killing people will make you much more of a target as security will attack you first.
This might stop the massed killing for 400Cr bounties and would mean killing people will make you much more of a target as security will attack you first.