I still wonder if the New Coke wasn't just some marketing gimmick designed to get free publicity. Advertising is expensive.
I don't think so. The New Coke rollout is a very interesting business school case study in how you can do everything right and still come out wrong.
In the 1980s Coca-Cola was concerned because Pepsi was consistently gaining market share. Pepsi was also increasingly being viewed as the cola of choice in youth demographics. Being the preference for an older generation is not a good position to be in when it comes to consumer beverages. So Coke decided they needed to take action to reverse those trends. Before introducing New Coke, they did extensive blind tasting panels, in which people were offered sips of various products, including traditional Coke, Pepsi, and various formulations of New Coke. They brought out New Coke after it was a clear winner.
For Coca-Cola, this was existential, because the market trends and demographics were against them. That's why they didn't consider keeping traditional Coca-Cola on the market. They weren't introducing an alternative; they were creating a replacement.
They were stunned by the blowback. What Coke missed was that what people liked as a small sip in a taste panel was disconnected with the market. Particularly as regards that slightly bitter bite of Coke. In the taste panels, with small sips, the sweeter, less bitter formulation won out. But in real life, consuming larger quantities, many people (such as I) craved that bitter bite.
The lesson to be learned is the importance of totally and completely understanding what your market is and where you stand in the market. You can link this up with the other thread on Red Lobster - understanding that Coke was savvy enough to recognize their folly and react in a timely manner.
