No, wait! It's dangerous for small people to run unattended through a restaurant, busy or not! That sounds more like it. I understand as a young parent you feel the overwhelming joy every time little Susie takes a step, my concern is, that you should realize how badly hurt little Susie could end up with a bowl of scalding soup dropped on her head. Allowing your, (admittedly adorable) little toddler to waddle their way through the restaurant is not okay. Children who are slightly older are even more dangerous because they move faster!
You see, the problem is: we can't see them! When you're carrying a tray filled with drinks or balancing six plates you have what is commonly referred to as a 'blind spot'. That spot settles exactly at the height of a small child. Even if the server is deft enough to manoeuvre around the child, it can still result in spillage. Are you the parent jumping out of your seat to offer to pay for the lost product? Probably not.
Beyond the danger: one must consider the other guests. A large number of people who have children spend their money selectively when dining. They leave the children with Grandma and head out to have a little quiet time to themselves. Their careful planning is thwarted by other parents allowing unruly children to run in circles around the restaurant - this is unacceptable.
Well behaved children are a rare delight in the restaurant industry. But for those parents who let their children run rampant, please, the by-ways in a restaurant are not for playing in - keep your child safe and out of harm's way by keeping them in their seats!