Here we go. Remember this is all IMHO, I have background in the stuff but nothing worth any merit. The OP wanted to know why I never wore the clavicle protectors that came with the Koerta.
Well, a couple of reasons really. The first reason I never wore them was because you couldn't wear a backpack with them. It made it very uncomfortable to have a strap on your shoulder.
However the main reason I didn't wear them was because they don't really serve a purpose. What I saw those doing was protection from an impact to the clavical and the trapezious muscle. For one, that is a very odd wreck but for two clavicals aren't broken from direct impact.
The clavical provides a joint for the shoulder to move (try to touch your shoulders together in front of you without moving your elbows and you will feel and see the motion). This is good because we can get a bit more range of motion, however when you fall and land on an outstretched arm your chances of breaking a clavical are huge. This is because the clavical has a crappy shape that was never made to take an impact horizontally. The physical shape of the clavical has a bend facing out towards your front, a small end attaching to the shoulder and a large end attaching to the sternum. So when you fall all that force (think of falling with your arms held out like wings and you tilt to the side, landing on your hand first), goes strait to that bend in your clavical and it just snaps at the bend. Hopefully it pops out and thats that, otherwise it could pop towards your body and cause a lot more damage. Think slicing arteries!
Landing on an outstretched arm is just about the worst thing you can do when you fall. You can break any bone in your wrist, fingers, upper and lower arm, shoulder, clavical...so...don't stick your arm out when you fall!
Sorry for the long winded answer I recently had a class that went through all this stuff about a year ago so its all still fresh. Hopefully some of that made sense hahaha.