Software engineers love cool new features, because programming is hard, and a cool hack represents a triumph of ingenuity and skill against the odds.

But computer users tend to prefer useful features to cool ones, because they use computers in order to get things done, and useful features help them do that.

Unfortunately, many apps suffer from an overfocus on cool, but I’m pleased to note (in a super-unscientific survey) that Google Groups reports only 24 results for the word “cool” in the mozilla.dev.apps.firefox newsgroup, where engineers and others discuss the development of Firefox, whereas “useful” appears in 85 posts.