Oxford-type shoes are the only suitable choice for a conservative business dress/ workplace environment. Wrong. I have been wearing boots with suits as a lawyer in a big firm, more and more, over the past year. Boots work really well with suits and are liked by the few people who notice.
Other possible rules that should be thrown out:
Black suits are only for funerals. Wrong. I wear a black suit to work about 1 out of every 30 days. It's a nice part of the mix.
What other rules should be tossed?