Architects seem to do some odd things wrt their own residence - I guess that is their time to indulge their vision- and design a one bedroom or worse, no bedroom open plan, build it on stilts, into a hill, underground, upside down...their houses often look pretty, big windows or tall ceilings but functionally can be just plain weird. Figures the architect moved out when got married per OP, which shows the arrogance of building a one bedroom SFR,, no utility other than to the architect - or that small set of buyers who this specific house appeals to.
Lot and location can sell an oddball house and it might depend too on how oddball the buyers themselves are....this is clearly not an average family appeal house, but in a trendy hipster area might have marketability. IF in a vacation area it is a great way to discourage pesky visitors cause sorry annoying cousin, there is no extra bedroom for ya...