There was a great study done at Wesleyan on indecisive decision makers. Past research has shown that indecisive people have trouble making decisions, have less confidence in their decisions, worry more, have more regrets (like buyers remorse), have lower life satisfaction, and more health issues (probably related to increased stress and anxiety). When making decisions, these people gather more information, spend more time gathering information, and even when they have an initial choice, they gather more information about that initial choice. They just can't "pull the trigger."
This new study looked at groups. What they did was put together groups of three people. All three were either decisive or indecisive (as measured on a well-validated scale from the psychometric literature). What they found that fascinates me is that when people were in these groups, the differences between decisive and indecisive people disappeared.
They speculate two possible reasons for this. It could be that indecisive people are better at collaborating because when you have less confidence in your own opinions you are more willing to listen to others.
It could also be that the reason indecisive people can't make decisions isn't that they are afraid of the mistake, but they are afraid of being responsible for the mistake. So in a group, that fear goes away because the responsibility is transferred to the other people in the group. Basically, you can blame the other people and they can blame you. So the indecisiveness goes away.