That's just it though... I'm not wearing actual protection. That's a suit designed for a cavalry charge and nothing more. Field armor was typically more compositions of mail, leather, and cloth. Maybe a plate or two somewhere meant to deflect slashing blows or later a fencing thrust.
D&D is basically a bad example of ANYTHING. It is nothing more than a simulation game extracted out of table top miniature wargamming that has fantasy elements patched onto it because the first round playtesters were reading Lord of the Rings at the time. But it had very little reliance upon or understanding of armor and weaponry. You're basically only lucky that I also know D&D - because it's not the universal point of reference you might think it is. At this point in time I'd wager more people know the rules of 'World of Warcraft' than have ever played D&D. That might even be true for FFXIV as well. Sure D&D inspired both games... but it's like you're bringing up the spoken language of the Phoenicians here to talk about Greek versus Finish grammar... Ya'll gotta be an expert to get why that's relevant or understand the analogies.
And just because something 'looks good' versus doesn't look good isn't a justification either for any argument because that's really subjective. We've actually seem some pretty horrible and massive injuries since the Iraq War due to a lack of using actual proper thinking about armoring against attacks as opposed to just using what looked like good armor... (and if I am to believe my trainers when I was in Basic Training, the SAME problem was a big issue in Vietnam - using tactics and equipment that 'sounded good' or 'looked good' vs. were actually tested cost the US a lot of causalities).
As you note... in fantasy you can defeat an epic monster with a piece of stale bread.
And... in actual physics... a suit of plate mail armor is just as useful against an archer as a bikini... As in: both are completely and utterly useless. There is a reason the English were such a force for centuries even BEFORE their sailors defeated the Spanish. They were not able to conquer anyone before their naval rise, but they amounted to a pretty solid defense after the reforms of the Normans, and the gesture of holding up 2 fingers is still an extremely rude insult in both England and France because of their archers ability to just go through anything. English friends of my generation tell me that at least into the 1980s, boys where they grew up still had mandatory Archery classes as a part of centuries of tradition that had once been the Island's military advantage.
So... as long as it is fantasy... we should just throw the pretense out the window and go with what seems most magical. We might as well all just put on sailor suits, be named after constellations, carry wants, and have to do cute dances as a part of our attack routines - given the proper inspiration for games like FFIV.
The moment any one of our characters faces off against anything other than a like sized humanoid figure with both parties using slashing or bludgeoning weapons... everything is utter magic.