This Service is an embarassment sometimes; there are far too many persons of considerable bulk waddling around who think they're in some sort of uniformed office job, and who won't take ownership of their self-inflicted unfitness. BMI can be an inaccurate method for establishing someone's healthy weight, as the OP indicated, but at least it's going to draw the MO's attention to some of the genuinely overweight - let's just call them fat - people. That has to be a good thing.
How about an annual body fat count? It's far more accurate, and the long-term benefits for health are considerable. Counting numbers on a BMI chart means little to those who don't consider their long-term health, but saying "23% of your body is fat and you're probably going to have a heart attack before you're 60" might kick some people into touch...