I'm skeptical of OBs and a lot of the medical interventions surrounding childbirth, and I believe a med free birth is better for the baby and mom. I feel very strongly about this, but that doesn't mean I don't understand that anything can happen during childbirth. I can believe what I do about what is the best birth experience without getting hung up on the fact that I have to have that experience or I've failed.
I took all those birth stories about women being depressed for months after the birth as cautionary tales. My reasoning for wanting a med free birth was to give me and my baby the best possible chance of having a problem free delivery and recovery. I wanted a med free birth because I didn't want anything negative having anything to do with those first few days and weeks. I realized that I might not be able to control that, but at least I could control how I would react to needing an emergency c/s, a NICU stay, etc. I tried to prepare myself thoroughly for all eventualities.
ETA-I realize after reading Kristin's response that my response doesn't take into account the scary moments that can happen during any labor that will stick with you. I think those moments happen to a lot of women and it leads them to question their decisions, but I'm not sure if that was exactly what the OP was referring to. I was thinking it was more along the lines of the birth stories I see pop up on the Natural Birth forum where the mother is upset for eventually agreeing to an epi and ending up with a c/s.