From a personal standpoint, I barely eat any carbs and I've lost zero strength despite dropping 25 pounds. Apparently the diet that has made me thinner and increased my energy and mental clarity is the "dangerous" one, and the diet that has made everyone obese is "healthy" and "balanced".
[1] The Obesity Code by Dr. Jason Fung
For example, it is believed that when we sleep our energy comes from fats. We are not doing anything exerting, so the process of (fat catabolism -> energy) >= energy needs. The brain needs glucose however, so it gets it from glycogen catabolism or protein catabolism (gluconeogenesis).
Edit: For some reason I cannot reply to the comment below. The recommendation is 45-65% based upon individual need. I've mentioned elsewhere in this thread that the brain can use ketone bodies.
I disagree that glucose = obesity as you seem to see it. Many, many things (nutrition, PA, stress, hormone issues, etc) are related to obesity.
A lot of what you emphasize is related to the lack of physical activity that the population no longer gets. If we truly want to solve obesity, it takes adjustments to diet and consistent purposeful physical activity. There's a lot that can be done with nutrition, but continuing our highly sedentary ways will always have consequences for health that nutrition alone will not completely solve.
Lets say for a second you're right and you need glucose, though. 65% is a really high number, and we basically know exactly what it leads to (obesity).
Would you have lost the same 25lbs. if you had just eaten less? In other words, does it really matter that you cut out carbs only? Are you chowing down on bacon and steaks?