I can remember many of these stupid "rules" coming out in the KM in the months before the convention. Even as a faithful Dub, I used to chafe against these silly restrictions.
In many areas of the country, families travel a great distance to attend a convention. This means staying in a motel/hotel and packing everything with you. The difficulty of preparing a bag lunch for a family in a hotel room (most of which do not have refrigeration or kitchens) is a strategic nightmare.
Think of the poor typical sister who has to get up about 5am to get her kids washed, dressed, fed, and prepared for an intollerably long day of sitting on uncomfortable chairs. If her husband is a "good Brother", he'll probably have an assignment and leave her alone all day with her squiming brood of unhappy children. She's got to find a way to feed her family AND her busy husband some kind of food that does not need refrigeration. Remember, Brothers and Sisters, large coolers cannot be brought into the stadium!
Jehovah forbid she takes them to the local McD's where they can let off a little energy in the Ronald McDonald Playland before the afternoon session.
The Pharasees could have learned a thing or two from the GB about adding unnecessary burdens to the flock.