This pressure was applied in order to extend the "benefits" of home ownership to individuals who otherwise would never be able to qualify. The stimulus this gave to the home building industry was enormous.
Both political parties were guilty of this pressure. Republicans believed home ownership would help people become more conservative, by giving them "something to lose."
Democrats wanted to help individuals who are normally shut out of the mortgage market by virtue of their poor credit histories and lower incomes. Such individuals come from segments of society which often vote Democratic.
As is often the case, Brooks has written a good column.