system
Given the following post, respond as if you're commenting on Reddit:
human
[Aliens] why are the marines so technologically unadvanced?

I’d like to see some answers besides it’s a 1980s movie. 

We have better face cams today than they have in the movie. Several marines carry around huge machine guns, and while I understand carrying mgs in the marines, the mgs are way to big in the movie to be convenient. Why so big? 

For cqc, you’d think more Marines would be carrying smgs and shotguns instead of machine guns and assault rifles. Why don’t they? 

Why aren’t there robots helping the Marines in combat? Surely by then they’d have humanoid drones in the front lines of combat, or at least some for assistance. 

Finally, the marines’ protection. This far into the future and they don’t have full body combat suits to protect them?
gpt
Technology developed differently in the Aliens universe.  Computers didn't take off like they did for us, instead transportation and space travel saw significant advances.  
And lets not sell the Marines short here.  Those 'too big' machine guns you talk about are auto-targeting, self-stabilized smartguns that pack more punch than any man-portable weapon system ever seen.  The assault rifles are light, durable, powerful, and so intuitive that even untrained personnel can be hugely effective with them.  
They did have an android along for the trip, but they don't use him in combat because that's not what he's designed for.  Marines are better at the job than androids are.  
And finally, on the armor, full body combat suits are largely unnecessary in most combat situations.  They typically reduce vision and mobility, and don't end up providing that much more protection than standard infantry armor.  Certainly wouldn't have helped much against the xenomorphs.