system
Given the following post, respond as if you're commenting on Reddit:
human
[Alien] Why was Weyland-Yutani interested in the Xenomorphs for their bioweapons department? Even if they were somehow utilized, they would be incredibly impractical.

It's been a while since I've watched through the series (didn't watch Alien Covenant), so I may be missing something. However, I do remember how the corporation wanted to use the Xenomorphs as a bioweapon. Still, I don't see the practicality of this. 

Sure, Xenos are pure, instinctual killing machines. It's probably cheaper to create a whole hive than it would be to mass produce Synthetic soldiers

But let's say you have an enemy encampment or even a whole hostile world. You drop a queen egg, with a few others in a sewer and let them do what they do best. 

What next? You can't enjoy the spoils of war when an entire planet is overrun with xenomorphs. You're just exchanging one problem for another. 

You'd think, as a money-grubbing corporation, WY would be more interested in developing a virus for biowarfare. You can cut through an entire population of colonists, maybe design the virus so it doesn't fester for long after the victim is dead, and then reap the planet of its resources/recolonize. 

What was so special about the Xenos (besides being aliens)  that they just had to get their hands on them for bioweapons?
gpt
If they can be trained, they become amazing weapons. An entire arc was dedicated to seeing if they could be controlled.

They have a unique gene structure that can (and was) used to enhance humans either directly via genetic manipulation or via performance enhancing drugs.

It might be possible to gene splice in a kill switch: either a enzyme weakness ala Jurassic Park or a drug/virus that kills them quick. Then it's no problem to retake the world, just send the kill switch or stop giving them the enzyme.

Studying them might allow advancements in acids, armor, polymers (they are partially silicone based after all), and their resin could be studied to make awesome construction tools and materials. Imagine setting up a series of poles and nets and then spraying some resin down to build walls and even buildings. Nightmarish, yes, but pretty durable and done in *hours.*

And finally, Hubris. People might just think they can take the hives afterwards.