I agree, my colonists will not, (ever, EVER!!!) go around picking up things on their own.
Currently I have my team of 7 or 8 "tanks" able to take some hits in power armor, with 2-3 with minis the rest with m-16s, I have my most skilled of 3 in dusters (because it's cool and doesn't slow them down much) with m-24s, and I have any other non-skilled colonist equipped with pistols and other easy-to-use, fast weapons.
The moment they start picking up stuff on their own will be the moment I'll have a seizure, having to de-equip the current then re-equip the old items.
Because every single one of them with M-24s would be a MAJOR problem, so is having to pay attention to each of them.
Besides, let's say it's done and I re-equipped every single one of them to my liking.
What's stopping them from doing it on their own again and again?!
Either way, HELLNO.
They are free to haul thing to a stockpile, but they won't equip anything without me knowing or I'll start executing them.
PS.: Equipment screen sounds useful. That would solve the "cannot see it on the map" problem *some people have* (because I sure don't...).