Why is aspartame important?

Why not? it tastes sweet and isn't bad for teeth and wont make people with Diabetes go Hyperglycaemic.

If you are referring to the Aspartame controversy which I am sure you are, Aspartame hasn't been proved to cause cancer in humans. while studies did find that there were increased cancer rates in rats fed aspartame, this doesn't mean It will cause cancer in humans. Dogs find chocolate poisonous, but humans eat chocolate in copious amounts without incident. so while aspartame may prove fatal to rats, humans can continue to enjoy the foul taste of the worlds most popular artificial sweeter.