If I'm drinking a can (1 serving) of course I'm gonna go with the option that tastes the best, but if, for example, I'm too broke for a (ridiculously expensive) 4 pack of Red bull and don't have the time to make the trip to buy knockoff energy drinks from Big Lots, and I am thus planning on drinking an entire 2 liter bottle by myself in order to load up on caffeine, I'd prefer it not taste totally disgusting, but I also don't want to drink 500+ calories.

50~ calories in 2 liters isn't that bad.