In the film it is made clear that the humans struck at the bugs first, and that also the bugs are responding because of human incursion into the areas they live in.

Hollywood has a staggering ability to see everything only in terms of approved archetypes and not realize when something only looks like it fits.

I watched this in the cinema when it came out. My friend and I both came out raving about how good it was. It was subversive, satirical, hillarious and terrifying.