Even if you work in an environment which borders on unprofessional, dressing this way has many benefits. People will regularly comment on how good you look. They'll take you more seriously. You'll gain a little more confidence and pride in properly accomplishing a given style. And you can use it for the rest of your life, until the point at which your centuries-old duds go out of style (which probably won't be in our lifetime). Other people in your workplace may notice this and make an effort to clean themselves up a bit, too, which may affect their interpersonal skills and work ethic. No guarantees, but it can't hurt.

Oh, and ladies go crazy over well-fitting clothes, especially suits.