Soldato
Whilst I'm definitely one of those people saying it's not good for a lot of people, I wouldn't say everyone should ignore it. It's like saying everyone should ignore their weight. That's all it is really, isn't it? Weight with some context of your height. You of course need more context and as I said above, for us in this thread, I think it is pretty useless, but I would imagine for a lot of people that don't exercise and generally live fairly sedentary lifestyles, if they're marked as obese they probably do need to do something about it.
I agree, as @fez says, for most people it's a pretty decent metric, and there generally are only 2 people who argue against it. Those who exercise and therefore have a greater than average muscle mass (average being compared to most people sat on the sofa for example) who get told they're overweight, and those who it tells are overweight and don't want to hear it so blame BMI as useless.
My reading puts me at 26.7 which is slightly overweight and the calculator suggests losing ~5kg to drop down to around 90kg to be at the upper end of the healthy range. I would say thats perfectly good advice and is where i'm aiming to be anyway. To say it's useless is a bit foolish.
I would agree with the range being pretty bizarre though. A healthy range for me is 67kg to 90kg. I guess at 70kg i'd be very thin and look a bit daft by modern standards but probably not unhealthy low which is what it's getting at.