Swimming is a very basic life skill that, if at all reasonably possible, children should be required to learn.
It's amazing what a difference simply being familiar with water can make. I have a friend who grew up super, super, super sheltered. His parents had never let him in a body of water larger than a bath tub, no swimming pool, no kiddie pool, no lake, no creek. Nothing.
One time a few years after high school he lied to his parents and came to the nearby lake with us to play on waverunners. He got on one, then had to jump off because it wasn't starting. He was wearing a life jacket and we were in about three feet of water. He slipped on the bottom when he landed and kind of fell into the water face first, and he just laid there, arms spread out, floating face down. After 10 or 12 seconds one of my friends grabbed him by the neck and pulled him up. Having never been in water before, he had absolutely no idea how to handle himself or even stand up, totally freaked out and paralyzed himself. We had no idea he was so bad in water, and neither did he. He damn near drowned while we were all standing there looking at him, in 3 feet of water.
He was so ill-prepared by his parents for life in the real world, even at 20 years old, that it was damn near criminal. You should have seen the first time we took him to a strip club. When he was 26.
It's easy for people to think they'll never need to know how to swim, but people drowned in some jaw-dropping stupid ways, ways they can't ever expect and ways that would be entirely prevented if they were at least familiar with the very basics of swimming. If it's at all possible to teach kids, it should absolutely happen.