I'd say it's newsworthy because people deserve to know the context that his contact with the girl started when she was 13, not 16.
This behavior has not been "fine" or "legal" for quite some time, but it was tolerated by individuals in a community, especially if the perpetrator had influence. The culture of tolerance has changed, that's it. And it hasn't even changed that much. R. Kelly is known to groom and abuse underage girls, and he's not currently in prison where he belongs.