I use Stage Panels when I want to block the default windows and pillars. They can be placed close to the walls than partitions and the pillars can remain visible while hiding other wall details.

Can't do much about the door since large furnishings being placed in front of it can block players from interacting with the exit object, leaving a teleport the only way of the house/apartment.

You can block the view of the ceiling by floating other items like rugs and the Troupe Stage but that can cause visual problems if you've added a loft area due to the lowered celiing.

And of course all the items used to cover the default interior features eats into the budget for decorating in general.

The dissatisfaction with the interior wall design has come up many times over the years but it seems to be required with the way the system has been programmed. I don't ever expect to see plain walls as the default in any housing added.