There is a valuable source of food growing right outside of everyone's doorstep. Native plants can provide you with greens, carbs, tea, medicine, fruit, and much more. The native plants are the best adapted at growing in your local area, and the seeds are freely avaliable from the plants. These seeds once collected from the wild can be integrated with any system and will (probably) outpreform other plants.
What's more, these plants serve as food and habitat for the native pollinators.
They help maintain the natural soil food web in its proper balance.
If we concentrate too heavily on planting non-native plants, our environment will quickly convert to a man-made environment with all of the pitfalls that invites. Diversity is key, but diversity of natives is paramount for a healthy system. While some plants may seem to have little value at first glance, if they are native, they have a value to the overall health of the system.
I am not one of the die-hard fans of planting ONLY natives, but I strongly believe that we must incorporate enough of them to keep the entire system in a healthy balance.
One look at the Corn Belt, or other parts of "America's Bread Basket" will show us the folly of overwhelming a region with imported 'exotics'.