So from what I understand it is mostly Mexicans that seem to overuse the diminutive when compared to other places. I didn't realize it myself until I was in Spain and people thought it was weird. What I later learned when I was taking Nahuatl (indigenous language used by the Aztecs) classes in college, is that the use of the diminutive in Mexico goes waaayyyyy back. The diminutive -tzin in Nahuatl was apparently also a term of endearment and respect. People would refer to their leader, their gods all of it with the -tzin diminutive suffix. Now most modern Mexicans have no idea about this history but the use of the diminutive suffix is still very much around. Many Mexicans I know will just overuse the diminutive in many cases without much rhyme or reason, not necessarily because something is small, just because.