Oh take it with no tone, just what I've found/another point of view/experiences dude. For the most part, I do agree with you, just have a different level of findings. Lemme clarify a bit to ensure clearer communication.
A) In my and a few others experience, the root cause being the armor is less common, and often due to wearing the armor incorrectly.
B) I disagree from my personal standpoint and experience - but I'm not saying you're not wrong either. I think its a two way street and very dependent on individuals - in many cases what you said is congruent. Personally, I notice my hits way less at combat practice or in my studded leather than I do with the "Plink!" on my plate. It's that added audible that helps me personally.
C) I agree with all of your factors plus more factors.
The armor system could use some more tweaks in terms of strata, given what can be created nowadays. You could replicate the plate Im wearing in 4 different materials off the top of my head - like, exact look - and have it be lighter, flexible, and in some cases if self fabricated, cheaper (most will be more expensive if you sale shop 18ga stuff). However, and I dont mean to reopen this can of worms - Arcane Armor will always be the best choice in terms of powergaming, safety, comfort, and OOG cost. Real armor will always bring about the best atmosphere. It's a seriously rough trade if you're interested in making a good atmosphere vs gaming hardcore. But in terms of material - Real Plate vs Fake Plate - I think there should be a difference, because of the effort involved with the real plate vs the fake plate. My current helmet is 2point base (4 total) although it looks like plate (its plastic). People who wear real, metal helmets (I have one myself that I do not use) are way more hardcore and are dealing with more weight/heat/etc. They deserve the bump vs my super light plastic that I can carry around with my pinky finger for an hour. I think the game could open up into a 5-6 tier system instead of a 3 tier system to better represent the material availability nowadays.
Safety I'm mostly with you dude, I think we need to tough out more stuff and bumps and bruises happen - but we need to not put ourselves in those situations when we have a safer alternative as bumps and bruises can add up to a bad time. Person to person, mostly I try to think of all situations in terms of 6'2" 200lb platemail (me) vs unarmored 100 lb 4'0" (few other players here) and want to ensure those two worlds don't end up colliding.