The article contradicts itself.  It says that millennials don't care about size but want bigger homes to raise families.  A solution in the article is putting a loft for an additional bedroom over the bathroom.  However a loft is a bad choice for a pregnant woman or a baby. 

The requirements that Denver has, e.g. burying utility lines, insufficient parking spaces, requiring the builder to include low income housing and requirements end up raising the cost and driving out families.

This is not rocket science.   When you impose conditions that cost more it raises the price.