I LOVE this idea. My family recently saw something like this in practice when we visited the Museum of the American Indian in Washington, D.C., and dined at their restaurant (the Mitsitam Cafe). You ordered your food at one of four stations -- one each for the regional cuisines of the Southwest, Northeast, Northwest, and Mesoamerica. The food options were diverse, freshly-prepared, presented in an upscale style, and quite amazing. (My family members enjoyed everything from roasted salmon and bison to rice pilaf with cherries and celery root salad.)
I don't see why the United States pavilion couldn't offer a TS restaurant with a menu built around a similar idea (perhaps with a prix fixe menu where each "course" offers at least one choice from each region), featuring the best of Eastern, Southwestern, Midwestern, Southern and Pacific cuisines. We have so much more to offer than burgers, fries and Ceasar salads! It's sad that our international visitors to the U.S. pavilion don't get to see that.