I go for the simplicity argument. Those additional terms don't really offer much more, especially since picking the right term involves predicting one's future finances rather accurately. In the case of 48 months, one can always take a 60-month loan and make extra payments. Those capable of predicting that 48 months is better for them than 36 or 60, are also capable of figuring out how to make additional payments.
Monthly payments for a $10,000 loan at 10%:
1 year, $879
2 year, $461
3 year, $323
4 year, $254
5 year, $212
6 year, $185
7 year, $166
Just looking at those numbers, it seems to me that 3 and 5 cover most of what 4, 6, and 7 cover. The real advantage to borrowers would be in 1-yr and 2-yr loans, for those with current cash flow problems which they will be able to fix soon. But again, people who can predict that, can take a 3-yr loan and make extra payments.
Edward