Some parents think U11 7v7 is too small

I’d ask the parents to watch involvement rather than pitch size. In 7v7, players are closer to the ball more often. Defenders have to solve 1v1s, midfielders cannot hide from possession, and transitions arrive quickly because there are fewer teammates to solve the problem for them. That can be very demanding football. U11 staying 7v7 is not about pretending they are younger. It is about keeping the game small enough that they repeatedly have to make decisions themselves. I’d also point out that 7v7 is the maximum format. You can still use smaller games in training to make the challenge even more individual. Bigger does not automatically mean more advanced. Better decisions under pressure are progress, whatever the pitch dimensions are.