I get what you are saying. The only reasons to house Sims that are not played are for immersion really. In my main saved game I do play rotationally with at last count 26 households so each household's houses and lots are meticulously furnished and decorated to suit their needs and asthetic pleasures. I also have all the premades present except a select few that have died.
But I do have saved games, yes plural, where I have either one household only or rotate between a small number of 3-4, usually part of the same family. In those saved games, where I don't delete the premades I don't really bother adding new households that I will not play or not part of the rotation. But if I delete all of the premades I prefer to add extra households into houses along with my played one even though I don't play them, so my household has someone to befriend and visit and even shop for potential spouces. I don't spend a lot of time decorating or furnishing their houses or lots as I either use the furnished houses already in game or download from the gallery.