There are a million homeowners who are underwater on their current mortgages yet are unable to take advantage of the HARP, HARP 2, and HAMP programs simply because their loans are not Freddie Mac/Fannie Mae owned. These boworrers are in good standing on their present loans and are of very little risk to the bank in a refinance situation even though their LTV is over 80%.
By expanding the mortgage refinance program to include non Freddie Mac/Fannie Mae loans it would give underwater homeowners the opportunity to take advantage of the low rates, putting money back into their pockets to help boost the economy and/or pay down the balance on their loans. It's a win for the banks as they don't have to worry about default and a win for the economy.