It is definitely not too late for that.

Ah, I’ve never seen any of the sequels. Might check it out, thanks.

I’ve never seen it that way - the opening pages say what the protagonist is doing. He’s landing on a planet to kill bugs, using all his ammo and nukes even though there are sentient beings living on the planet.

All because it isn’t cost effective to evacuate the ammo as well.

Immediately following that we move to the viewpoint of the teenager being brainwashed.

As such I think the movie did a decent job of adapting the story, even though we lost those awesome mechs and dropships.