Yeah, our place is not THAT old. I think it was built around 1993.
Currently, both the laundry closet and the furnace closet have hollow-cored doors with a small louvered panel on the bottom half of them. Our neighbor from the downstairs apartment replaced the door to their laundry closet and put in solid doors with no (apparent) ventilation, which sparked the thought that maybe a louvered door might not be needed
We are replacing the doors because, currently, we have a bunch of cheap, flat, hollow-cored doors that look terrible. We wanted to upgrade to some nicer doors. Both rooms currently have hollow-core doors with a small Louvered panel at the bottom.