For the chest padding I do think it is personal preference. With that being said if it is your preference to have the padding because getting shot hurts then maybe you should play in a pump league where there is no chance of getting hit by 12, 13, or 15 BPS.
I say this even with my personal health situation. I have had a pacemaker for 3 years, after the surgery the doctors told me I couldn't play sports that were "physically straining". Nothing against what they say but they almost didn't do the surgery in the first place due to me not having 'signs' of a low heart rate and probably having this condition since I was young. So with 15+ years of competitive ice hockey, long distance running and baseball and just having 3 years of competitive paintball under my belt I wasn't going to be bother to stop with my adrenaline addiction. I wore chest protection for the first event back after the surgery it was nothing but a bother. From then on I have played as I always normally have. Only this time with a small metal box under part of my skin close to my left side of my chest, which has seen many paintball's break on it. Does it hurt yeah but so does getting hit anywhere on your body. If your playing so sloppy that your getting bounced on the chest then maybe you should worry more about how to play your bunker tighter or get training to run quicker. If people are running down doing run throughs on you then your team needs to tie up the loose ends so it doesn't happen. The safety for your arms and knees for sliding is understandable and also if there are health conditions which might be similar to mine. I doubt that the sales of chest protectors reflect the amount of paintballer's with extreme health conditions though.
Maybe the next step in cheating is to hook up the ramping to the pacemaker so the gun preforms better.....