Standard & Poor’s this week joined other rating services in lowering minimum mortgage servicing fees required for several categories of loans securitized in the non-agency MBS market. Many mortgage bankers have pressed for an across-the-board reduction in servicing fee requirements that were developed decades ago for Fannie Mae, Freddie Mac and Ginnie Mae programs. Since that time, technology has driven down servicing costs, lenders say, forcing servicers to carry unnecessarily high servicing fees on their…