Cassava, from what i have seen, is ingrained into the cultures of Mexican / African / South American diets and they are proud of it.
Their persistence, imo comes from a lack of alternatives and again a culture practice of growing a usable and edible product. Visiting some places in Mexico / Brazil you begin to understand people are just in "survival" mode - use what's available.
The toxicity issue is also common in legume crops such as lima / red kidney beans which are also common in these cultural diets.