I don't mind having a Single U-Turn once in a while, although I prefer Doubles.
Taking a look at all the used Single U-Turns:
Lorena & Jason started the fourth leg of TAR12 almost two hours behind, and had no realistic hope of catching up anyway, (since there was no HoO) unless someone made a huge mistake.
Amanda & Kris reached the TAR14 U-Turn in last place anyway, so one would not have expected them to have survived at that point in time.
Kisha & Jen came closest to surviving on TAR14. If they had not gone to the bathroom, they might have survived.
Joe & Heidi were forced to do a VERY tricky Detour option on TAR16. I thought that task seemed way too hard (although I know very little about Morse Code, so I can't be sure) and I think that U-Turn was inappropriately placed.
Carol & Brandy probably were the second closest team to survive (aside from Kisha & Jen).
So of the five properly used Single U-Turns:
2/5 teams reached the U-Turn in last place anyway
1/5 teams were forced to do a really hard task
2/5 teams came reasonably close to survival, and one really should have survived
So after all my unnecessary rambling,
what I'm trying to say is that I don't necessarily believe it is impossible to overcome a Single U-Turn, so I wouldn't mind seeing a couple more (although I definitely prefer Doubles). Only 3 teams have ever been U-Turned and arrived at the U-Turn ahead of at least one other team, and one of those 3 teams almost survived, and another would probably have been relatively close.