Why is there a demand for Bunk Beds & spiral staircases

Sims 1 2 and 3 had spiral stairs and they are compact and extremely handy and have a huge amount of potential for builds of all types. And likewise, Sims 3 had bunk beds and they are also compact and really handy for child sims (also modders have created functional bunk beds for TS4).

Cars aren't as functional gameplay wise, rather something that adds verisimilitude, which you could argue is something that is lacking. Loading screens and cars aren't an issue. Certainly wasn't an issue in Sims 1 or 2