Agreed; I've often wondered if this is a result of early CS classes usually expecting students to handle weird/bad inputs. It's only natural for a programmer to want to write a program that gracefully handles all reasonably bad inputs, like nulls. So we're taught early on to write defensive code that handles those. And that's fine when you're writing short, academic programs. But when the complexity goes up by a few orders of magnitude trying to gracefully handle that null value 10 levels deep in some parsing logic maybe isn't the best thing to do. Old habits die hard, however.