I believe there was political pressure put on Freddie and Fannie to make loans to low income people. Certainly greed played a big part of the financial melt-down, but that does not make greed and profit a bad thing. The problem is that if the government says "make these loans" and then guarantees then, the motivation is in place to make the loan. Many of these loans were made for a nominal fee and then "sold" to another institution that managed the payments for a fee. Then when it was recognized that there was no way they were going to pay, the government stepped in and bought them back.
Take your pick as far as who put the pressure on. Barney's committee was in the race, but both teams are on the committee.
The scary thing is that they are right back to putting pressure on again to make low income loans.