Nutritious isn't the concern - hornworms ARE nutritious, just as superworms are. It's not good or bad, wer're talking about - it's QUANTITY. We can not replicate their diets, we can try, but we can only try. No matter the type of feeders, we have to be concerned with caloric intake - feed an adult veiled chameleon 5-10 crickets every two days, and the chanceds are thathe will get overweight, and die within 3-5 years max. It is extremely common for an overweight chameleon to just start to decline and die fo rno apparant reason - this is what fatty livers do to reptiles. they do not function like we do.
A chameleon that is always hungry, eating JUST enough food to provide calories to function and move about, will probably live twice as long as a chameleon with any noticable "plumpness" to it.
Superworms made up about 60% of the diet of my big male veiled who died last summer at 8 years old. He was very light for his size and was always hungry. I've seen fat chameleons that ate only crickets - it's quantity of calories, NOT fat content.
hornworms ARE very nutritious. Fact. Too much nutrition is why things get fat. Something like a bacon double cheeseburger would be "bad" for you because it is so nutrient dense. But, for someone who wants calories, it wouldnt' be bad. Same with hornworms, superworms, etc. healthy, sure. but If I were to feed them every day, that's like eatign a healthy meal 10X a day!
Quantity. too much, and your chameleon will die sooner.