For your application they are perfect. Elsewhere they are still much much slower than a human while they could be much much faster. The floor plan needs to be

For your application they are perfect. Elsewhere they are still much much slower than a human while they could be much much faster. The floor plan needs to be hard coded. When a new house or office is wired gadgets can be embedded in the walls, floor, doors to get the positioning system accurate to the mm. Movable chairs can also get a bit of electronics, not sure if it even needs power. Larger objects that are moved less frequently can be positioned on its map manually. It needs an idea how delicate or robust objects are so that it can move extra slow or extra fast. It needs to know if the bottom of the wall is cleanable and do so. It should know when to clean then if no one is there race up and down the hallway. If the bottom of the walls and/or doors are cleanable it should know to move faster. In some industrial applications there should be rails on the wall or floor and possibly rubbers for it to drive into if the floor is slippery. A combination of large and small cleaning robots would be more effective.