You are not a very "wise" guy, are you? Are you in education? Your post sounds like a statement from someone who is a PE teacher and doesn't feel like they get enough respect.
First, no matter how important physical education is...the regular classroom education ABSOLUTELY is more important than physical education. Second, the requirements for a PE teacher on a day-to-day basis pale in comparison to that of a classroom teacher. A PE teacher does not have to grade papers. A PE teacher doesn't have to worry about Gateway exams. A PE teacher does not have to differentiate lesson plans. I could go on and on. A high school PE teacher has an inordinate amount of time to properly educate his students and focus on coaching his/her sport as compared to a regular classroom teacher. So, yes, I stand strongly behind my solution...and most administrations follow it if they can find the qualified person for the reasons I stated above.
Now, on to the other point you brought up...obesity among our youth. Obesity in America is a problem that reaches far beyond teaching children about proper diet and exercise. It is a by-product of many factors such as technological advances, busier lives, instant everything, etc...not to mention genetics. These factors, and human nature, will continue to make obesity a problem that will not go away any time soon...no matter the education.
Before you get all defensive trying to defend PE teachers...I dare you to spend a year trying to teach a math, science, or history class PROPERLY!