We could see that it is really hard to avoid Terrigen cloud because Inhumans usually aren't near this cloud. (Civil War 2, Uncanny Avengers, Moon Girl and more series, x-men series also)
If Terrigenesis would be controlled then less people would die and they would have a choice (they could try gain superpowers or not)
right now they don't have.
inhuman deaths - we only know that some people died from what i know.