I appreciate it might be tricky to animate, but ever since curtains appeared in sims 2 I've wanted to option to open and close them, as in have a sim manually do it - it looks weird if they're open at...
Simlogical managed to make Sims 2 curtains that opened and closed. However, I wish they would make it an official feature in Sims 4 (or if it is too late, Sims 5!) It would also be nice if they made official windows that opened and closed. I would also like to see glass sliding doors, and wooden pocket doors.