Because that's how they are built in the US. I didn't need the extra space, but for the money, there wasn't much choice, really. I would have loved to rent a house half smaller at half price, but none were on the market. I barely went upstairs. My dog occupied it, at least.

I could have rented a townhouse for $300-400 less, but then there are different constraints. Small or no yard, tiny kitchens, no garage etc.

I was perfectly content with a 2200 sq ft ranch in Henderson Nevada.