If you wanted to actually use it day to day though, it would cost so much more. Just the temperature control for such area would be either super expensive or require a complete redesign of the space to split it into lower floors.
It would, but that's partly a matter of size, and a large house will cost a lot to heat or cool as well. I'm in the UK (cool climate), and there are a lot of smaller chapels which have been converted to use as houses quite successfully.
