I'm sorry to tell you this.
Stevia is Satan's ball-sweat! (This is how improv works. You make a joke, I go with it. Isn't this fun? Now you go. Oh yeah. You can't. Now I have to make all the jokes. Great.)
I like to think that stevia is made when Satan squeezes the ball-sweat straight from the sack of a guy named Steve. I also want to believe that Steve is a marginal offender, like, he was fined once for minor tax fraud and momentarily worshiped a graven idol. He's just kind of a douche, and his ball-sweat tastes the worst, so Satan butters up his hands and goes to town, kneading his balls until stevia seeps out of chodebox, runs down his spider-leggy pubes and into a vat marked, 'Straight to Vegans'.
(That was an unnecessary shot at vegans, it's just the word was the funniest one I could think of, and also, they're not going to notice how bad stevia is compared to their food, because they eat things that taste like sacks 'n' holes all the live long day.)
I guess the point is, I agree. I tried stevia in a soft drink, and it wasn't too bad. I guess I was fooled by all the other vile chemicals masking its flavor, because when I bought some packets of stevia extract to replace the sugar in my coffee, I used two and put the rest in the garbage where they belong, the whole time curious as to why it didn't say, 'Put Straight in the Garbage' on the package.
Short Answer: There's got to be some plants out there that are sweet, don't kill you, and don't taste like bush runoff. Agreed.