I was taught in journalism school to mention the subject's age when possible. It doesn't take a lot of space and can be valuable information in some cases.
Well your journalism school by definition is ageist.
It's important context. It tells you a lot about the events that a person has lived through that inform their opinions. I'm too young to have any real memories of stagflation and Reaganomics, for example, but I can tell you all about the NASDAQ meltdown of '01...