I don't drink a lot of carbonated beverages anymore myself, opting instead for tea or water. Coffee in the morning, of course, black — and slightly less viscuous than Valvoline 10W-30. Anyway, my point is the Great Coke Switcheroo Part II won't affect me much. But there are people who are really passionate about this. I get that... and given Coke's extremely similar tactic and its spectacular failure about thirty years ago, one would think they'd have learned from it and not tried to make the same mistake again.
Well, let's look at that a bit.
I was a mere youngster when the New Coke fiasco took place, and for awhile I had an actual can of the original Coke and the supposedly identical Coke Classic. Despite claims to the contrary, the ingredients were different. The biggest change was the substitution of high fructose corn syrup for sugar. Let's not be naive here — when the second-largest ingredient in your product is swapped for a completely different ingredient, two things are absolutely going to change: the flavor and the manufacturing cost.
Coca-Cola has been around for a long time, and you could argue they are one of the most successful marketers ever. The red can with its white swoosh thing (or "dynamic ribbon device" as they call it) is an iconic symbol recognized all over the globe. Given that, it would be extremely foolhardy to change what works, whether taste or appearance. But in 1985, they did just that. Why?
Hint: high fructose corn syrup is very inexpensive when compared to sugar. So for the 1985 change, I'd say it's as simple as following the money.
As for changing Coke Zero to Coke Zero Sugar, the new name of the soda, there's no sugar to remove (zero sugar — get it?), so it's not that. Maybe some other ingredient has become too expensive and the profits aren't what they once were. Maybe there are too many people like me who have steered away from carbonated beverages as a whole. I don't know. But I'll probably get a can just to see what all the fuss is about. Maybe that's the game... getting people to just try it again.
That's not good in the long-term, but it creates buzz in a mature industry... and if that's the goal, they've definitely succeeded.