Because real people like to go to the beach or go running or a million other outdoor activities. And some people even like the look of a tan, or want to show off their bodies. Or people don't want to spend their time thinking about that stuff and have other priorities. That is my point about the narrow advice. People have diverse goals, and there is a lot more to going out in the sun than optimizing your vitamin d levels. Treating people like we're all farm animals that need some standard, dictated care formula works for nobody