dark chocolate, like dark beer, coffee, and red wine, have anti-oxidant chemicals. However, that only makes them a better choice over milk chocolate, light beer and white wine.
its like when McDonald's changed the type of oil they fry with...and tried to call it 'healthier'.
None of these things are 'healthy'...but going with the new fryer oil is "less of a health risk" than what they used to use. Same with dark chocolate. its not healthy, but it at least provides something beneficial to the body besides calories.