When you think about it ties are a totally unnecessary fashion statement. I think people look better in them and have a preconceived idea of the type of person who doesn't wear one to certain places, but they really serve no purpose.
Actually a tie (to me that is) can help "liven up" a sharp suit, such as a black or pin-striped (and the pin-stripes can actually match the tie as well) As long as the tie is not likened to a clown tie or is too ostentatious...One should be able to notice it and get a good compliment, it shouldn't other people's eyes or make them squint.
It can also serve as a statement, on a interview a nice tie, the employer can remember that tie and you. Or the chick that you work with that you are flirting with. For instance, I knew a woman that was very attractive, but always had dudes. Her favorite color was purple, so I had various purple tie and shirt combos, again nothing, ostentatious, but very subtle. She notice, and would comment...and the rest was history...