AI can pick up the best weapons from the ground

[KSS]

I suggest implementing or borrowing the mechanic from BAI where the AI selects the best available weapon. This could be made a toggleable parameter. 
The idea is that the AI would analyze nearby tiles within a certain radius of its position for weapons on the ground. If the alien is in relative safety (not seeing or able to attack anyone), and the weapon on the ground is more powerful, accurate, faster-firing, etc., the AI would pick it up. 

For example, this could allow players to drop weapons for allied locals, letting them swap their farming tools for something that shoots. That could be fun  
On the other hand, in some scenarios, players might prefer replacing passive camping tactics with a more aggressive approach to prevent enemies from looting better weapons from fallen units. 

In Brutal AI, this works well despite enemies having positionally driven behavior. In OXCE, however, AI is mostly not tied to cover, so this feature should perform even better.

[Yankes]

AI already can pickup weapons in OXC but it is deliberate disable for most items to prevent grifting.
Same for civilans, there was report where CIV pickup rocket launcher and blowup your solders when he try "help" you.
Not mentioning angry armed chickens :>

[Alex_D]

Yes, the infamous rocket launcher-armed civilian team-wiper 
Said friendly fire events are reserved for x-com soldiers exclusively! 

I'd suggest to have a different value of weapon attractiveness but applicable to civilians only, precisely to avoid those mass casualties scenarios.

On the other hand, a civilian picking up a heavy plasma is a good thing. Can it be mind-controlled and fire said weapon?

[KSS]

Same for civilans, there was report where CIV pickup rocket launcher and blowup your solders when he try "help" you.
Not mentioning angry armed chickens :>

As mentioned above, is it possible to reduce the value of weapons with AoE damage? 
Perhaps introduce a linear dependency, for example, the higher the shot accuracy — the higher the chance the AI ​​decides to pick up explosive damage weapons. This way, rocket launchers would be picked up by units that can actually shoot. 
Chickens also have terrible shot accuracy Maybe set a minimum firing/strength (or other stat) check to prevent them from equipping  weapons.

[Meridian]

As mentioned above, is it possible to reduce the value of weapons with AoE damage?

Yes, each weapon can already have a different attraction value.