Like the GP said: in offices the floor is often a big open space where light from windows can extend a long way. But once you start dividing up that big space into smaller residential units with walls, that light gets blocked.
I don't think bedrooms really need windows and in some ways they're preferable with the light & noise reductions.
Even if that's solved the bigger problem is earthquake code. These older buildings aren't up to modern code and significant renovations would require structure changes.
Bedrooms are where people spend majority of their time when awake. It is where kids play, do homework, adults work from home, watch youtube, read internet.
Unless we are talking about super large appartment with tons of rooms, they need windows
Even if that's solved the bigger problem is earthquake code. These older buildings aren't up to modern code and significant renovations would require structure changes.