When figuring your BMI, doesn't your bone size and structure affect the calculation?
Yes. That is why the optimum BMI is a range of values, not a single one.
No single value can give a complete evaluation of a persons state of health. There are well-documented, researched and proven links between body mass, size and projected wear on the body. The BMI values are a range accounting for normal variations in individual bone structure or density. Being "big boned" (HOW did you prove that?) is not an excuse for obesity.
Just as being ultra-fit is not a guarantee of longevity (accidents and disease still happen), being over-weight is not a guarantee of an early demise. HOWEVER, excessive demands on the physiological functions of a body from unnecessary mass (fat accumulation) DO impair many other functions as well. Over time that will result in a higher probability of different health problems.
SO, don't discard the value of the BMI over a technical calculation quibble! But, don't get obsessed with a particular BMI value either. It's not an "on/off" switch to life.