I seriously doubt they were created for that purpose.
I rather think it's a side effect that is neglected because a) it's hard to proof and b) it's impossible to sue the company for it.
The effect why sweeteners seem to make people more hungry is rather that it makes people crave sweet foods. There's nothing bad in it, the only thing is that people who do not understand nutrition drink half a liter of diet coke and then get sweet cravings, they eat ice cream, chocolate whatever.
I eat sweetener in a Yoghurt mixed with banana, oatmeal, cocoa powder, cinnamon and split almonds. If you ate that, it's impossible to be hungry anymore. 
So it's rather the lack of nutritional knowledge in people than the sweetener itself that leads to eating more. It's a question of self control, too.
Most artificial sweetners has resulted in more complaints to the FDA due to side effects than any food additive in FDA history. Must tell you something there.
As for making you hungrier, they do. Artificial sweetners tell your taste buds that , " sweet stuff has arrived," which to the brain means, " nutrition has arrived." When the artificially sweetened drink or food reaches the small intestine, the receptors find no nutrition. A message is sent back to the brain saying, " There is nothing here, we've been tricked." The appestat (the part of your brain that triggers satiety) sends a message to " keep eating because we need nutrition to help process all this fake food and run our body."
I see it a lot with people who drink diet sodas all the time. They live off of it, they are addicted. They can't get off the stuff because the neurotoxic effects. Food companies put chemicals in your food to make you hungrier so you will buy more.....
