Area under construction does appear on the OpenStreetMap website. I think it's a brown or grey area.

My philosophy is that OSM should map the world as it is right now, not as it was or as it will be. Additionally people consume OSM data via hundreds of different renders so I don't try to make my edits look a certain way on any given render. I map according to the documentation and if the render doesn't display something correctly, that is on the render, not OSM.