I would like to see 4m wide, and or 8m wide/tall.
Better I would like to see ways to link things to make them however you wish. Make them cost a lot more EI a 2m wide door costs 8Y, 2Z, and 30a. Make a 4m take 42Y, 6Z and 180z. Then make a 8M one take like 126Y, 24Y, 540z. This way people wont just go crazy on what they can do without putting a LOT of resources into it.
I would like to see them mesh up better too. Gaps in floors, and walls. I'm not sure how all this can be done but it would be cool if they could.