Athletics changed my life for the better. Gym instills a sense of teamwork and also teaches games you'd look pretty stupid not knowing lmao. Like if you ever go to a beach, it's helpful to know how to play volleyball so you won't be the only one out of your friends sitting it out.
Now I know there is a vast, vast difference between gym and athletics but both cater to a person's physical needs. Human's are not built to sit in a desk 8+ hours a day. We're built to run, to jump, to swim, etc. Gym gives a healthy outlet for that. With childhood obesity as such a huge problem, getting rid of gym would most certainly make the issue even worse.
Games provide an easy way to learn basic skills. Basketball gives you hand eye coordination. Football teaches you how to memorize and execute plays under pressure (and depending on how good the other team's defense is, that could be a LOT of pressure). Soccer is a whole lot of running, and also teaches you how to pass the ball. Point is, every game helps with something and if you're athletic chances are you're able to swim. I wouldn't get rid of it or even try to reform it (except maybe improve football helmets and make other stuff cheaper) because I think it's a healthy outlet for kids.
Also, every school has drugs and pregnancy. High School is a bit of a party. But I noticed that the most well adjusted kids aren't the ones who parents keep a death grip over and prevent them from ever going to a party. Those are the type of kids who end up in college and typically binge drink because the only beer they've ever had was the ones they snuck out of the fridge (if even that). Same with sex. Most people get pregnant because they have no idea what they're doing.
Now I'm not saying you should do all the drugs and have all the sex, but I'm saying being exposed to those elements helps mature you a bit. Because nearly everyone is going to drink in one point of their life, and nearly everyone is going to have sex. But you don't want your very first drinking experience/adventure to be at a frat party where noone knows you or your first sexcapade to be relying off your knowledge you gained during freshman sex ed.
(Always remember fellas, wrap it before you tap it).