You should want to sing “the end” from the rooftops, not vomit in the sand between the back of a portaloo and someone’s million-dollar Cape Cod-style McMansion.
The why factor tells reader things about your characters. Readers learn who people, and they connect more deeply with the story, such as in “The Gift of the Magi” when writers show instead of tell.
Reading makes you a better writer by improving your memory and concentration, boosting your language skills, and giving you insight into your field or genre.