They're the Microsoft Word of houses. Famously, people only use 20% of Word's features, but that subset varies depending on whether the user is a legal secreta

They're the Microsoft Word of houses. Famously, people only use 20% of Word's features, but that subset varies depending on whether the user is a legal secretary or elementary school teacher or whatever. McMansions have all the features - the 3-car garage, the almost commercial kitchen, the vast gathering spaces, the rec room, the home office, etc. Not everyone needs it all - but some car guy will demand that third garage spot or some foodie will demand the oversized Viking appliances or some family with multiple kids will demand the big play area, etc. This way these houses meet the needs (and way beyond) of 90%+ of the upper-middle to upper-class homebuyers, so they retain their value and are way more easy to sell than the weird custom 1800sqft home with 4-car-garage, or 1-bedroom condo with commercial kitchen, or whatever.