Damn you Curious Bros
In order for the Sims in this household to properly use the hallways, I butchered the bathroom. It worked, kinda: they now use the hallway to go from one side of the bathroom to the other. Awesome.
Fun fact: once a sim has learned physiology, he gets magically more muscular while eating chinese takeaway, as I've witnessed with the why-cook-our-robot-brings-us-pizza Curious brothers.