Why do people always have to give their kids nicknames?

Lately, it seems like everyone's trying to come up with a nickname for every single name they consider. I can understand for names like Katherine (Kate), Eleanor (Ellie), Elizabeth (Lizzy), and Bethany (Beth), but names like Regan, Natalie, and Gloria don't really need nicknames like Rae, Lia, and Ria. It's irritating. If you give a kid a name, just call them by their name.