I realize I really don't change the hairstyle of my sims, especially males, as they get older. But now with the more "trendy" hairstyles, it's a bit weird to have my male elder wear a fade and quif...
Usually only in the "Child - Teen" age transition is when I change their hairstyle. I do that because it reflects some people I knew IRL that suddenly have different hairstyles in High-school.