While a D & C is scary and an unhappy option--all that invasive [censored] in the middle of such a tumultuous, emotional time--sometimes it is the best way to make sure the uterus is in the shape it needs to be, especially if you're going to try to get pregnant again.
I had a miscarriage in Aug 2005. I was allowed to miscarry naturally and did not have a D&C.
I got pregnant again in April 2006, and miscarried in May. My new doctor wanted to perform a D&C because he was concerned that my uterus may have not fully expelled the lining or "products of conception" from my previous pregnancy, therefore making miscarriage much more likely.
My mother in law is an OB nurse and she was a) surprised the first doc didn't do a D&C and said she wouldn't have been surprised if that's what caused my second miscarriage, and b) that after the D&C, she would be willing to bet that I carried any new pregnancy to term.
Well, I'm pregnant now, 4 months after the last miscarriage/d&c...I've only just found out yesterday, so I don't know the specifics...but if I make it past my first trimester this time, I'm going to be thankful we agreed to the D&C.