IMO, stevia can have a superior flavor profile to sugar for certain specific use cases. I really like it in ice teas because the sweetness comes on slow and that makes the drink seem more refreshing. Also, I can't taste any aftertaste because the tea leaves themselves produce a mild, pleasant bitter aftertaste which is conveniently paired with the longer-lasting sweetness of stevia.

That said I can see why stevia would not work for Coca Cola because you don't want the underlying bitterness of caffeine to hit you first without any sweetness. Coke needs to hit you fast. The thing about coke is that it's all about the first sip. It's as much about flavor as it is about freshness. The first sip must overwhelm your senses and energize you.

With ice teas, on the other hand, the flavors don't have to come on straight away because you're looking for freshness first and foremost. I think the pleasantness of it is mostly about cooling and soothing. You don't want it to hit you too fast; so a slow-onset flavor profile works better.