Obviously no food is inherently "better" than another, but your body needs certain things to survive and for the most part simple sugars is not one of them.
Could you get lean eating solely simple sugars, or utilizing them as most of your calories? Absolutely. Calories in, calories out. Might other parts of your overall health be hampered by this? Yeah, maybe.
Should people eat sugar if they want it? Yeah, no doubt. Is "go ahead enjoy sugar" good advice for everyone? Not so sure about that.
The problem with studies is the environments are typically tightly controlled. Human behavior is not.
Eating mostly Twinkies but getting only 1400 calories is going to work for weight loss and then subsequently cholesterol readings (would be interested, however, in hormonal changes over 10 weeks). But what about the people who won't or don't stop at 1400 calories? These are the folks to whom I would be careful in imparting said advice.