If you're asking me personally, it's because I don't have any problems with eating too much sugar so I would never want to introduce an artificial sweetener into my diet when it carries potential strange health risks.

I think people get hung up on finding sugar substitutes when the root is eating sweet things constantly. You don't have to eat and drink sweet all the time. Many modern diets (not just n. Amer) are totally overindexed on sweetness.

Drink water, eat good foods, enjoy a bit of jam on your toast or whatever here and there and get lots of exercise and you'll be fine. You don't need aspartame and xylitol and stevia to be healthy.