Of course, I do love the Dark Ages. They are a fascinating period of study; to me they are the age of the Huscarls, the Shieldwalls, the Thanes and last stands, of the Dragon Boats and the basis for Tolkien. They also gave us the Northmen, the discovery of America, and the epic Battle of Maldon.
...and the English language. The Staffordshire horde is making those "dark ages" look pretty shiny.
I agree that Dark Age as a age that is shrouded in mystery because of a lack of evidence will be come an increasing misnomer, but I still think that as a description of life at the time, Dark Age is fairly apt....