So, I really like designing ships for maximum efficiency (well, who desn't), and a major part is door placement. But there is one time-consuming problem I have run into when building a large ship, and that is removing the automatically placed doors to get door placement right. Going through all connections between rooms and modifying doors when needed is possible but quite lengthy, especially in a major rework or a new build.
So, seeing as doors are quite cheap, a button to remove all doors (in blueprint mode) would be great. Maybe, if that is possible, make it remove only newly placed doors on the first click and the rest on the second click. Or something like that. A similar idea would be to include a button or keybinding that removes all similar objects when held while deleting.
Something in the same vein would be that whenever you have selected doors, any rooms not connected to the one you are hovering over with your mouse are highlighted somehow (red maybe), this would save people like me from embarassing fires spreading in areas that were given fire extinguishers simply because they are not connected.
Well, there go my ideas for improving usability a bit. Good luck with this impressive project!