They are still popular for kids, and I like them. This is especially true when our kids are playing outside at dusk, or when we walk the dogs after dark. I used to work in law enforcement, and part of my job was directing traffic. On a cold day in the fall, I put on a black jacket to stay warm. It did not have any reflective material, and all I had was a small flashlight to catch the attention of drivers. Fortunately, traffic was slow, but I almost got hit. I like our kids having Nike light up shoes on their feet to increase visibility.
There are a couple of things about increasing visibility to drivers. The first is contrast. The second is movement of that contrasting material. Reflective materials and light up materials provide the contrast to the dark at dusk and at night. Bright fluorescent materials provide contrast during the day. You should have a little bit of both on your person at night to be safer. The movement of arms, legs and feet more easily catch the attention of drivers when the contrasting material, or light up material such as Nike light up shoes, is moving.
I even heard a story once a few years ago of a criminal who was wearing light up shoes being caught by the police because he was easy to follow. Well, I like that visibility on our children when they are outside in the evening. We supervise them outdoors, but you know how kids are. A distraction can have them do something unwise. We only have about five cars go down our street in a day, but we never know when it might not be one of our neighbors who are always looking out for kids. They look for theirs and ours. Delivery drivers, lost people and others could venture down our street. The kids are so used to so few cars and it always being a neighbor that I get worried they might get hit.