Why?!

Tell me this, please, why in the world is it impossible to make an artificial sweetener that does not taste like crap? Look at all the great things we've accomplished. We managed to create a whole new country and separate ourselves from England. We put a man on the moon. We have our first black president. We have cured polio. We created a network of computers that allows us to talk to people all over the world. We have done so many great things. So, why can't someone create a sweetener that has zero calories and doesn't leave a nasty aftertaste?