Answer: “We’re game development pussies,” Bethesda’s Todd Howard said at a QuakeCon panel on Friday. No really, the engine in Fallout and Elder Scrolls runs into AI problems if ladders are introduced, and the developer just works around them.
“One day, we tried to figure out why we wanted ladders so bad because we don’t really need them,” Howard told the panel, according to IGN. “It just felt like we’re game development pussies because we can’t do ladders.”
Howard indicated the studio’s revisited the subject repeatedly but finds it couldn’t do them without fading to a loading screen. Considering that’s the S.O.P. for most exterior doors in Fallout, introducing load screens to the interior of a structure just to take a ladder is kind of silly, especially if you can use stairs.