Why would any corporation want its customers to be happy?

Some businesses certainly don't need to care. A restaurant in central Rome has an infinite supply of new tourists to feed, so they don't need to worry about whether anyone wants to come back. At the other end of the spectrum, a monopolist knows that customers have no choice and must come back regardless of how they're treated.

YouTube has elements of both: there's a near-infinite supply of hopeful Internet video stars, and they also have a near-monopoly on video viewership. They might still want to keep stakeholders happy because these issues tend to brew for a long time until they blow up into public consciousness. (Facebook's promiscuous spreading of user data was known ten years ago, but they only took action now. Damage control would have been easier earlier.)