I believe it's a good measure for statistics over population, since it's easy to measure and tend to work for a large number of people.
On the individual level tough, you really don't need to be a world-class athlete for BMI to become less relevant for you, contrary to what some commenters seems to imply.
For the last 10 years I've been to the gym around 2/3 times a week, walked a lot more, cut down the junk food, and yet I'm 10/15 kilos heavier than at my 'fattest'. I'm far from being a powerlifter or a professional rugbyman, yet when I see people around me, I'm usually the beefiest guy in the room.
I do believe that some people went overboard with "body positivity". In the same time, as a french guy living in Paris where the expected look varies from 'slim' to 'extra-slim', I'm glad to see more things for people with an even moderately wide frame.