I seem to remember seeing some science stuff about sweeteners being a problem because by their nature they fool the body into reacting to them as if they were sugar -
Tricking Taste Buds but Not the Brain: Artificial Sweeteners Change Brain's Pleasure Response to Sweet
Banning stuff as the drug wars show is not a great answer to problems, regulation can help but education (or indoctrination if you like) I think is what makes the difference. My 7 year old, who does gymnastics and generally runs round like a dynamo all the time, rarely eats sweets - she'd rather eat a bowl of frozen peas - and doesn't have a spare ounce of fat on her, was telling me the other day that the ketchup was healthy because it only had a few calories.
@pimple8 Getting people to be more self-aware etc. is a long and difficult road and would incorporate a quite radical shift in our whole society. Most people have little idea from moment to moment of what their own face is doing let alone anything else.