[esyir]

It isn't anywhere near obsolete, not as far as I've seen in both scientific and medical contexts. BMI remains heavily used in many nutritional and disease related studies and remains a common metric in healthcare and public heath.

It's imperfect, but generally correct. More importantly, it's easy to measure. Accurate except for outliers isn't as much of an issue as you think it is, especially as these are generally already accounted for by its users.