due to rationing still being in place for a while, and food was pretty dire still in the 70s and 80s.

That was definitely true of Japan, too, where ramen was a poverty food popularized out of necessity, that then became a foundation for innovation up the value chain.

Same with Korea, where American occupation (and a whole history of foreign conquest and occupation) made for interesting combinations of Chinese, Japanese, Korean, and American ingredients. Now Spam is probably bigger in Asia and the Pacific Islands than it ever was in America.

Same with many American food traditions being rooted in the slave trade (see West African food culture being remixed with new world ingredients and exported right back to the Americas in what would become southern U.S. and Caribbean food).

And of course there's the broader discussion between the interplay between fine dining, casual dining, home cooking, industrial/mass production of prepared/processed foods, etc., that often creates its own foodways.

I'm biased in that I think the cultural mixing in the Americas makes for better food innovation, where so many American classics are some sort of mix of German, Italian, Mexican (which is itself a mix of indigenous and Spanish cuisine, while Spanish cuisine itself has significant North African influence), Caribbean/West African, with even a little bit of French Canadian influence mixing in on Cajun food.

Merely importing ingredients is only part of it. There's a lot to be said for techniques, tools/equipment, and traditions, too.