Space for teams to warm-up, including goals. For a country that spends so much effort getting kids participating in soccer, we make it difficult for them to practice shooting.
Play areas for kids on the sidelines to go play some pickup, like a mini-pitch. It would be good to have one of these that’s accessible when the complex isn’t locked up, too.
Shooting/passing walls. At most empty goals at a soccer complex I see kids taking shots. Just think how many more shots they could take if the ball bounced back to them. Somehow our country got an abundance of tennis rebounding walls for tennis players to practice their skills on, but that concept has escaped the soccer community.