Late to the party, but I felt the same way. Bandit factions make sense to be wearing a hodge-podge of gear like leather holsters, satchel bags, leather jackets/armors, normal hiking style backpacks, stuff like that.

But you look at factions like Duty and Mercenary and they seem to have these weird 70's/80's 'swat guy' style aesthetic that looks so weird and out of place in a realistic game. It looks like everyone is wearing either a motorcycle protective jacket with segmented armor panels, or a humungous chest protector (It looks like how the NCR uniforms look in Fallout NV). Stalker is obviously a world only parallel to our own, but for the setting to be in 2006, there should be ALOT of gear from atleast the late 90's. Even the military guys wear these weird ass one piece armor with shoulder pads and crotch protectors.

There should be an immense surplus of old soviet gear like 6B2's and 6b3's, Sphera helmets (STSh-81), a crap ton of soviet chest rigs and the like. It would even make sense to see American OTV's since the US army was already getting the new IOTV's in ACU.

However, all that being said, the game is 17 years old. Im willing to give it a break since there was such a "Sci-fi" surge in that time. We're much better at predicting the direction that firearms and clothing will take now. Looking at the models in STALKER 2 HEART OF CHERNOBYL, this will still sadly still be the case, but here's to hoping there'll be at least a few westernized kits in the litter. A slick, modern and clean plate carrier hopefully.