By allowing the first floor to see the space on the second floor effectively opens up the space as well. Though this means to waste some space, I believe it is worth it. This is also another example of using white to make spaces seem bigger.
"I try to carry books with me wherever I go. Their weight has become like ballast against the churning sea of modern life, where so many real things are vanishing, and so many beautiful things are being made invisible..."
Under floor storage - doesnt need to be deep.... but uses space otherwise not used. Oliver Peake: Japanese Bed “This was an interesting commission. The client wanted an entirely sunken bed with hidden storage and invisible heating!"