It’s not an optical illusion: our nation’s houses really are growing. According to the U.S. Census Bureau and NAHB analysis, the median size of a new single-family home increased to 2,471 square feet in the first quarter of 2014—up 17 percent from the first quarter of last year. In fact, new homes have been getting larger since 2009.

Not only are homes bigger, but they also are equipped with additional features. Nearly half of new single-family homes started last year had four or more bathrooms; 22 percent had a three-car (or larger) garage.

These houses are larger and have more amenities because a specific type of home buyer currently dominates the market: the affluent consumer with an attractive income and a high credit score. These households are the ones that can afford to spend the median $282,000 that a house costs today and have no trouble securing financing.

Unfortunately, such statistics tend to obscure a troubling aspect of today’s housing market. Other creditworthy households that can afford a mortgage and want to purchase a home are running into a major obstacle: tight credit. Current conditions have meant that only people with very strong credit scores—58 points higher than all U.S. consumers, according to Fannie Mae and the Federal Reserve Bank of New York—are securing a mortgage loan. By comparison, the gap between mortgage borrowers and all consumers was 33 points in the early 2000s.

This disparity has led to a fundamental imbalance in the new-home market. Right now, first-time home buyers account for only about 16 percent of all new-home buyers; historically, about 29 percent of new-home buyers were purchasing their first home.

In the short term, such an imbalance may be largely benign. But over the long term, it could spell big trouble for the nation’s housing market and our industry.

There’s no question that the reckless lending that contributed to the housing market crisis couldn’t be allowed to continue. But in trying to guard against a similar situation, lenders have moved too far in the opposite direction. Creditworthy families who can afford a mortgage and who want to purchase a first home are facing often insurmountable obstacles.

This is a complex situation affected by a multitude of factors, but ultimately restoring the housing market—and home finance—to normalcy depends on restructuring the nation’s housing finance system.

The NAHB has long advocated for and strongly supports a housing finance system that relies primarily on private capital and has a federal backstop that would be triggered only under extreme circumstances after significant levels of private capital are first exhausted.

Such a system would breathe life into the housing sector by providing a consistent and affordable supply of mortgage credit—including 30-year fixed rate mortgages—as well as financing for new single-family and multifamily construction.

Bipartisan legislation introduced earlier this year by Senate Banking Committee chairman Tim Johnson, D-S.D., and ranking member Mike Crapo, R-Idaho, would meet this goal. The Housing Finance Reform and Taxpayer Protection Act of 2014, which passed out of committee in May, would maintain a proper level of government support while encouraging responsible lending to creditworthy borrowers. The NAHB is working hard to help move the bill forward, and I urge all in the housing industry to reach out to your senators and ask them to support this important legislation.

Without such reform, the gap between the housing haves and housing have-nots promises to get bigger, and prospective first-time home buyers will find it even more difficult to enter the market.

It’s always important to keep today’s buyers in mind when building and planning for the future. But we can’t let the strength of one group of home buyers obscure the needs of others. To be healthy, the housing market must meet the needs of diverse populations of both renters and buyers because, as we know, one size does not fit all.