Mexico has such a long culinary tradition - plus the weather to produce a vast range of produce. The Spaniards brought in some old world traditions, which later mixed in with the local Amerindian diet of beans and chilies. Add the fact that Spain was a major maritime power for 200 years, bringing in traditions from all over the world. I am a little surprised that the food is so plain down there, but Panama was a major slave trading area, plus transit point between two oceans - probably did not help matters much.
We spent 10 days in interior Michoaean this summer - the food there was so much better than the coast area it is hard to describe - the smallest vendor seemed to put out really great stuff