I've been curious about the just-less-sugar idea myself. Like how would a Coca-Cola "dry" taste? Maybe the fact that nobody is offering this just means it doesn't taste good.
Some other countries have products with less sugar than the US's version. Fanta is a noticeable one. I just want a late afternoon beverage that isn't alcohol, doesn't have a crap ton of sugar, has no sugar substitutes, and isn't too heavy on the caffeine. Might go back to decaf.
Coca-Cola tried at least twice to market half-sugar Coke (C2 and Life). But instead of just doing half-sugar, they added aspartame and stevia respectively to compensate...