While link clicking I came across the following: http://safecastle.blogspot.com/2012/04/perspective-on-cost-of-emergency.html and the advice given is that rice and beans are a very boring diet. Yup, we can classify that one under the "no duh" theory of culinary preparedness.
Now, what isn't addressed is that with a little additional investment rice and beans can be "interesting" instead of "boring." Because across the planet rice and beans are the staples of many varied ethnic diets. Take rice and beans out of Mexican cuisine and you still have Mexican cuisine. Take rice and beans out of Middle Eastern cuisine and you still have Middle Eastern cuisine. But you miss out on refried beans and humus, arroz con pollo and Israeli Rice. That isn't even including the massive number of East Asian ethnic cooking styles. If you know how to cook with a dutch oven, a wok, a stew pot, a frying pan, and have access to some basic restaurant spice rack you can make even plain rice and beans delicious.
My point is that if you base your survival diet on rice and beans you have a lot of culinary ground to build on. Buying restaurant size containers of curry powder, coriander, oregano, cumin, chili powder, dried herbs such as sage, parsley, chives, cilantro, and even such basic staples as salt and pepper can vastly expand on your taste options. If you can stock dried/preserved/grow vegetables like carrots, celery, onion, garlic, broccoli, cabbage, you can once again vastly increase your taste options. Vegetables aren't very good for calories, but they are great for nutrients. Want a sour taste? Stock some vinegar to bring a little more pucker to your dishes. Want to add some heat? Keep some chili peppers or sauce on hand.
So at the end of the world, break out the rice and beans. Then break out everything else that you need to make rice and beans the basis of a diet that has a variety of tastes. Then pity the poor folk who are eating a diet based on wheat berries.