Whenever an event widely viewed as a "market failure" occurs, the fight over interpreting what happened is intense and politically charged.
The subprime "crisis" will be an example. As you try to follow the debate, you may find this post by Ilya Somin on Volokh useful: it summarizes the argument that zoning and other land-use restrictions played an important role.
And don't forget that government-fostered lower underwriting standards also probably contributed.
(This is drawn from my short piece that James Pethokoukis posted on his blog. I thank James for inviting me to contribute.)