If your FP conflicts with the BoG time, ask for a later BoG time or swap your FP (or eat somewhere else).
When you're handed a return card, you either take it or you don't. You don't stand there and say to the CM, "Oh wait, this is for 1:55-2:05? This doesn't work for me! Can you dig through your whole stack of cards for a different return time?" Especially when there's people behind you pushing and shoving their way up to the CM to try and get one of those precious return cards. So that rules out one option.
Changing your FP+ time? You mean the reservation you had to plan out 60 days ago, waiting until the clock hit midnight so you could frantically book all the reservations and times you wanted? Now you have to change it so it fits around your lunch, parades, shows, other FP+ reservations, possible dinner reservations, and breaks at your hotel? And since it's already almost the afternoon, most of the better FP+ options are taken? Sure, that'll go over well with most people. I was definitely thrilled that our FP+ for Space Mountain was switched to Buzz Lightyear (the attraction with the longest line at the time we switched it).
Eat somewhere else? That's the most realistic option you suggest. But for some, that isn't considered as an option. Most once in a lifetime visitors have heard about BOG and want to dine there. And who can blame them? It's a beautiful restaurant, filled with lots of magical touches. It's something that just feels very "Disney", and the food isn't bad either. These guests may not read these forums. They may not read up on WDW much at all, besides what their travel agent or friends tell them. And why should they have to stalk forums and blogs just to eat at one quick service restaurant for lunch? It's not like Disney is blatantly advertising this new system. We were there the first week they were implementing this, and had absolutely no idea until we hiked back there. And especially with the amount of advertising Disney does featuring Be Our Guest, people come to the parks thinking they can just eat there for lunch, since it's listed as quick service and quick services work by standing in line.
You make it sound like it's very simple, but it's not. Have you been there and experienced the new system? If you haven't, I don't think you should be making negative remarks about other people's experiences, and making it sound like they're doing something wrong by complaining about it. It's one thing to sit at home on your computer and read about this system. It's a whole different thing to actually be there in the moment.