Reason being is because what if we only had a select group of food, and out of the select group of food (that probably would be that big) some of it goes into a famine. We would then lose a large selection of food, and with 6 billion people to feed, it wouldn't work out. The Columbian Exchange does complicate the way I look at food and what “culture” it comes from. The best example is the Italian one. Original Italian food wouldn't have tomato, but because of the C. E it now does. And typically that is a stereotype associated with Italian food.
As for Ireland, I do associate potatoes with it, but I know without the C. E Ireland wouldn't even have potatoes. Thanksgiving wouldn't be the same without the New America food. Pretty much everything on that list is thanksgiving. From the new world food, it'd be hard to live without cranberries and chocolate. From the Old World broccoli, apples, bananas. I think the Columbian exchange does continue today. One example is diseases. Some of the diseases that occurred spread to other people because of the C. E. The spread of agriculture also continues! This also helps our population to keep growing.