I would rather see compromise resulting from a lack of confidence than a bad outcome resulting from overconfidence, at least in dressing. If you want to treat something as a purely aesthetic pursuit, then it makes sense to push it as far as possible. Is clothing a purely aesthetic pursuit, though? I don't treat it as such. I admit that I treat it more aesthetically than some people, sinceI am in a culture/career that encourages sticking out. Even so, I see it as at least 50% social communication.
I think we can basically agree that we'd like, socially, to be seen as well-dressed. That can't always happen. Which of these is more tasteful:
To be seen as 90% well-dressed, with the caveat that you failed to pick a bold enough shirt to counterbalance a bold suit/tie/square?
To be seen as 90% well-dressed, except for an over-confident shirt which pushes things over the top?