I'm curious as to why American-Chinese food changed between the 1970s and 1990s. In my area, I started noticing the change in the late 1980s. Egg foo young larg

I'm curious as to why American-Chinese food changed between the 1970s and 1990s. In my area, I started noticing the change in the late 1980s. Egg foo young largely disappeared and egg rolls were replaced by spring rolls. My impression of the newer style dishes was that they had less meat, were greasier, and were generally more well-done. The last time I had good egg foo young or egg rolls was almost 30 years ago. I had assumed the change was due to a massive wave of immigration in the 1980s. But if all of the food was a deliberate creation for the American market, why didn't they stick with what was already popular?