Ordinary people (and this includes doctors and other medical professionals) always want something simple because reality is too complex. BMI is simple, which is why it's been so widely adopted. We've known from the beginning that it was hopelessly inadequate, but alternatives require people to deal with several variables and ordinary people hate that kind of thing. So despite all its many flaws, BMI will lurch onward for the foreseeable future. What we ought to be doing is using a composite score: percentage body fat, blood pressure, VO2 max, bone density, heart calcium score. But who wants to try to do all that when BMI is so easy?