I think this is a brilliant idea. Wood doors could be the only ones that could by kicked down. Troll monks can kick down Iron doors. Monks 13 ability is kicking down stone doors. Metal doors can be melted with fireball, burninghands, acid. Stone doors can be destroyed easily with picks and hammers. Arrows of destruction (an arrow enchanted with uber fireball) candestry any door, and at higher levels blow open walls (you join the low mountain village (ADOI =) and attack the high mountain village. you shoot your arrow of destrucion mark III and blow a gaping hole in the wall as well as evaporating that annoying moat). Than of course there are non-passable enchanted doors.
Most of the special doors would not be randomly generated. Maybe metal doors can be generated in Royal vualts, or something like that (btw, do you think randomly generated graveyard room are plausable?).
With random generated grates, maybe in order to get to the down staircase you need to pull the lever in the center of that gnoll and hyena filled vualt. there would always need to be two levers though, one on either side, so if you accidentaly teleport out of that room, you can get back in.