The reason that it is so difficult to build indoor maps in Forge is because Forge is fundamentally broken. It's a great feature that wasn't implemented well. There is no reason why it should be so hard to make small adjustments. I cannot figure out for the life of me why the hell objects are automatically picked up when you select them. It makes it near impossible to make small adjustments without just starting over again. Also, why are certain items limited to certain maps? Foundry has lots of nice structural features, but where are all the decorations? Radios, camping stools, etc. It might not sound like much, but it can really spruce up a map.