Those amenities are rarely used in North America. The problem is zoning, fire, and building codes make it impractical to build a bunch of 2.2k square foot units instead of the current mix of 500, 700 and 900 square foot units. Double stairway requirements are a big onerous regulation, especially when we already mandate sprinklers. What we need for families are more developments like the interwar upper west side in NYC, 4 bedrooms, natural light, bigger than 1.5k square feet, single stairway.