So here's what I don't understand... Why build a house on the ground in a floodplain in the first place? If it's going to float up a pylon to 12 feet when the

So here's what I don't understand... Why build a house on the ground in a floodplain in the first place? If it's going to float up a pylon to 12 feet when the water rises why not just put it a story off the ground on stilts to begin with? Seems like it would reduce some of the unnecessary complexity this house has and maybe even reduce the needed footprint since you could do things like park vehicles under the house when a catastrophe is not in progress... Anyway logical reasons why this was not considered?