Then what was bad about it?

Can't speak for Jack, but I remember Eighties and Nineties pop-nutrition advice associating sugar consumption (inaccurately) with hyperactivity and (more accurately, but with caveats) with tooth decay. As regards specific sugar-rich foods, I don't recall soft drinks ever being blamed for obesity during my childhood, but candy, cake, and cookies all were at times -- though this might have as much to do with fat as sugar.