>>/57757/
They don't shoot back.  They're just...  bugs.  And the visual style of fighting bugs oddly gets way more repetitive than fighting the bots.  Mostly because regardless of what the original topography of a planet looked like, bug worlds are covered in nasty bug nest stuff.
Also I fucking hate bug and animal type enemies in video games, because by design they have to just swarm you in massive numbers, and be right on top of you 100% of the time.

With bots I get to exchange fire with them, and call in napalm airstrikes, like it really is Vietnam.
And I get to call in those millions of tons of ordinance directly on my head half as often.