Well, I guess that one way of viewing it, is as extremely important feedback.
As Queen Victoria, and Queen Elizabeth understood, the monarchy exists in its current state only at the behest and good will of the people.
They've been given the feedback that okay, lots of people like the expensive soap opera, but an increasingly vocal minority dislikes it sufficiently to get off their chuffs and go and protest against the institution, at the very limited forums for direct feedback available to them.
All three children are old enough to be involved in a discussion (age appropriate of course), about the privileged position they enjoy, why they enjoy it, and why it could be jeopardised if it became sufficiently unpopular.
If they don't wish their children to be potentially exposed to a negative reception of the monarchy in the future, they might want to withdraw their children from such events. Of course, then they'd miss out on the 'cute wee kiddies' premium goodwill payout, and people might feel freer to express their anti-monarchy sentiments at them. . .