Most houses have simple stairs, without storage place, but if the owners would see these pictures probably would have thought it would be useful to make such an idea. The space under stairs is valuable and it goes unused most of the times. It is better if you can make some drawers under the stairs that fit the stairs perfectly and do not affect in any way the function of the stairs nor do they prevent walking upstairs. I think this is an original and great idea to use the space under the stairs for storing slippers, magazines, tools, socks and so on.