Some modifications I’m intending to make to our current home:
Translucent light switches with power to an interior LED so you can see the light switches in the dark.
Dedicated wall switch in every room to turn A/V equipment on or off.
Stack of spare TP rolls on their side behind wallboard, with neat hole in wallboard at bottom of stack (to grab spare TP roll), and opening at top (behind a picture frame) for refilling the stack.
For kitchen sinks: panels/cabinet doors for access to the plumbing on the back side of the sink, so you can work on the plumbing from a (relatively) comfortable position. (Possible even for sinks next to outside windows, although there are obvious security issues with this one, and possible code problems in new construction.)
There are lots of this sort of thing in Japanese design, especially in the infamous “rabbit hutch” apartments where space is at a premium and clever design is more valuable because of it.
Other clever ideas from readers would be appreciated.