Have you met most Americans?
Just kidding. When it comes to the function of why we take carbs, I'm with you, I'm not sure it matters all that much for the majority. Probably post workout I'd stick with white rice, but for the rest of the general meals I'm just not sure it matters. It may make a small difference if you're SO elite that a 1% advantage changes something.
I will say that high GI carbs do raise my blood sugar much quicker, and I feel far less satisfied about an hour after eating. One of the biggest problems with my diet is getting enough fiber in, so I tend to go towards brown rice for that benefit alone.
I heard this but I've never fact checked it, so Google around before you believe it, but I've heard that if you cook a white potato (normally a high GI food), let it cool completely, and then reheat it in the microwave it actually changes the complexity of the starch in such a way that it does not spike blood sugar reheated. Again, do a little research before you believe that. But if it's true it seems to imply the high versus low GI food game is maybe a little bit more subtle than some of that older research implies.
C-