Planetside 1 had hackable doors. It was an additional layer of defense. You had to hack your way in the door (pick the lock, if you will) and certs would speed up the process dramatically. It lent itself to a bit more strategy so the offense could not just walk in unabated. Who the heck designs a military base without a (lockable) door? So what happened in PS2 that made the Auraxis overlords forget to build doors this time around? Were they drinking the Nanite Juice a little too hard in planning? Note: Shields don't count, PS1 had those as well, in addition to doors.