Agreed. I don't think that the risk of executing innocent people is a strong argument. There are plenty of innocent people charged and are serving time. You will never have a foolproof system but as someone has mentioned, there are enough scientific methods to help cases nowadays.
Don't get me wrong, I'm not advocating hanging left right and centre but I'm pretty sure there could be a hybrid system in place where some crimes(I.e child molesters, repeat sex offenders etc) can have the capital punishment apply. This would be after a jury rules the charger guilty. No matter what anyone says, capital punishment will deter crime, it lowers the risk of repeats and reduced tax dollars spent.