With the average rate on a 30-year mortgage falling to 3.29% last week, financing a home purchase has never been cheaper. …Yet housing is juicing the economy less than it used to, some economists say. Housing never fully recovered from the 2008 financial crisis, and low rates won’t cure its ills. Higher land costs, restrictive zoning, scarce labor and tighter lending standards still limit construction. …If housing starts continue at the current yearly pace of around 1.6 million and new families keep forming at the rate of one million annually reported by the Census Bureau, home builders may finally begin filling in the gaping housing hole created in the 2007-09 recession. “That’s a good sign, but is it enough? No,” said Mr. Khater, of Freddie Mac. “The lack of affordable housing is the biggest economic obstacle we face right now. [a WSJ subscription is required to access the full story]