https://hbr.org/2011/04/why-most-product-launches-fail

Flaw 3: The new item exists in “product limbo.”
The Lesson: Test the product to make sure its differences will sway buyers.
Coca-Cola C2
For its biggest launch since Diet Coke, Coca-Cola identified a new market: 20- to 40-year-old men who liked the taste of Coke (but not its calories and carbs) and liked the no-calorie aspect of Diet Coke (but not its taste or feminine image). C2, which had half the calories and carbs and all the taste of original Coke, was introduced in 2004 with a $50 million advertising campaign.
However, the budget couldn’t overcome the fact that C2’s benefits weren’t distinctive enough. Men rejected the hybrid drink; they wanted full flavor with no calories or carbs, not half the calories and carbs. And the low-carb trend turned out to be short-lived. (Positioning a product to leverage a fad is a common mistake.)
Why didn’t these issues come up before the launch? Sometimes market research is skewed by asking the wrong questions or rendered useless by failing to look objectively at the results. New products can take on a life of their own within an organization, becoming so hyped that there’s no turning back. Coca-Cola’s management ultimately deemed C2 a failure. Worldwide case volume for all three drinks grew by only 2% in 2004 (and growth in North America was flat), suggesting that C2’s few sales came mostly at the expense of Coke and Diet Coke. The company learned from its mistake, though: A year later it launched Coke Zero, a no-calorie, full-flavor product that can be found on shelves—and in men’s