The idea behind it was that the keypad-activated doors would require keycards or passwords or something, and that they could be locked down remotely from the control room. I ended up dropping that idea because the map was already getting too complex and time-consuming.

But now that you mention it, it does seem to be possible to get around them without even having to go through any keypad-activated doors. I sometimes get a bit caught up in adding interconnectivity in my maps :)