Which is why people pay for PE, business and first class. But whether the 'brand' is as powerful when it comes to deciding between the same cabin on different airlines is questionable. Passengers' behavior patterns, and how they respond in surveys, suggest that, generally, they won't pay more to fly on another airline in the same class of service, which means that certain elements (free cookie and a drink in economy or a different seat design in business) are of no particular value for them. While the brand's reputation is important, the factors that affect it are not what many here believe they are.

Yes, you did. But my question was not really 'why should airlines care about their brand and reputation?'. It was more about why should they care about some specific rankings which criteria is heavily tilted towards very specific elements that most people do not care about when they make purchasing decisions. When a falling Skytrax ranking does not affect your financial results, or when a reviewer who swore off flying your airline turns around and buys a ticket from you because you offered the most convenient or the cheapest flight, why should you care?