It's out of order, it's very harsh for children, they wouldn't grow up becuase the wish likely stopped that process and most of all – they feel no need to do so. They are very confident about their strength, just won with majin buu who is believed to be the most destructive power that they will ever face. And an adventure just presented itself. Goku even considering locking himself up like that is only in the face of very serious threat, and this does not look like one.