BMI question

I was looking at this chart for BMI and I can't figure out what the hell it means in relation to general health:

I just checked on a calculator that said at 188.5 pounds at age 30, 6'1", BMI = 24.9. The scale they provided said BMI was too high? I exercise daily: jiu-jitsu, running or weights. I don't get it...

My wife with no exercise, passive smoking comes in with 21.1 BMI (good to excellent on the chart) weighs 126, 5'4". What the hell?

My wife is trying to use this silly paradigm she got from her work to show she is in good health (she is, but I'm trying to give her motive to start exercising regularly). I tried explain to her muscle density and how it doesn't account for regular to vigorous exercise - what else am I missing?

It means nothing in relation to general health, feel free to ignore it. Most atheletes would be in the overweight or obese category. It's based on mortality figures, mostly dealing with old people.