It's not a problem for the assemblies. It's a problem for the conventions because the venues pressure the society to have the stands open and their response is "we don't need to everyone brings their lunch from home" but when they see people leaving to get food it ruins that.
It really annoys me that everyone doesn't get that. 50% of my congregation went out for lunch this summer, and their reason was that they were staying in a hotel and couldn't make lunch. Crap! It's such a horrible witness.
Suggestion when staying in a hotel: If you can't do PB sandwiches or you want something more substantial, find a deli or other small place near your house that will make you lunch at breakfast time. Pack a cooler with ice bags (the hotel will put them in the freezer for you overnight). We found a deli near Nassau coliseum and bought our lunch with our breakfast. No rules were broken, and everyone got killer sandwiches that stayed fresh until lunch time.
Yeah, it's real simple. Just go out before the assembly and get your food. Keep it wrapped up and wahlah!
I know for a few years they just told us not to go out. That should have been enough reason not to. Now they had to start explaining why not because just being told not to obviously wasn't good enough for some reason. Obedient in what is least here people.