You'd need that space to go somewhere, so the rest of the floor would either need to be a meter thick, you'd need a big protrusion into the lower floor, or you'd have to have it on the ground level with nothing underneath.
You'd also be pretty locked into the floor plan layout, and there would be no place to put a TV screen that's visible from the whole seating.
Pretty cool looking, but also pretty impractical with modern buildings.
