One problem with the viewing area idea is that little kids running around loose create a safety hazard, especially with servers carrying trays of hot food. A viewing area would only increase the number of kids on the loose.
And there's no way Disney wants to give up the income generated by two tables, especially since there's tons of free viewing right next door.
How 'bout adding Crush to the Coral Reef? (Like Remi over in France.) "Duuuu-de.. get your stinking feet off the table, man...... Like wow, so ruuuuude....."
The moral of this particular story is to speak up right away and firmly set your boundaries. Get a manager involved if necessary. There's no need to be made uncomfortable because some parents won't control their children.