BMI is a decent way to figure "fitness" or whatever you'd want to call it, but not really universal.
For example, I'm somewhere in the 5' 11" - 6' 0" range, and to use BMI, I'd have to be roughly 180 lbs to not be "overweight". The problem being, there's no way I could get down to 180 lbs without starving myself, because of my build. My "ideal" weight (i.e. the weight I think I look the best at, and physically function the best at) realistically hovers around 190 lbs. Right now I have a little weight to drop to get there, but if I tried getting down to 180, it woudl take a toll on my overall fitness. I'd end up having to drop 10 lbs of pretty much muscle, which wouldn't be productive.
Long story short, there will be exceptions to every rule. BMI isn't perfect, but short of a complete examination by a doctor, fitness trainer, or something to that effect, nothing really is. People also need to trust their body as well, when it tells them what is right for it. I'm a little over 200 lbs right now, and feel like I drag a bit. If I can get back to 190, I know my body will feel loads of improvement.
The dedication you show to any particular console or company is inversely proportional to the number of times you have gotten laid. If you get laid enough, even if you prefer a certain brand, you just don't give enough of a shit to argue about it on the internet.