Fundamentally, I think Fannie and Freddie as they existed pre-crisis represented a bad implementation of the bad idea that government policy should promote the construction of large single-family owner-occupied housing. But the concept of pro-suburbanization industrial policy seems very broadly supported in American politics.
From Yglesias » The Pricey Bailout
Good point. Much of this boils down to an American love of cars and the hatred of mass transit. Cities don’t make sense without buses and trains. If you start there then the only policy than can support that is suburban sprawl.