I agree that dress codes are unnecessary, as most are based on the level of hosting. In other words, there are expectations for a black tie affair, and too many wedding ask for "black tie" when they aren't hosting a black tie affair at all.
By nature, weddings are dressy affairs. Cocktail attire is always acceptable unless the venue is, say, a barn or other more casual setting. Evening weddings are dressier than earlier weddings, and so on.
Then again, with what some people wear to weddings (jeans, logo tees, etc.), perhaps some people DO need to be told. I've just always believed in the ability of most people to judge an event and dress appropriately.
