The point is that a system based on (and that's based, not dictated by) reality is always going to be preferred to an ass-pull system.
From what I've seen, ToadyOne is atleast heavily leaning towards more and more realism, not away from it. And that's good for everyone, because the fact is, there were no perfect weapons, armour, tactics, etc. in the middle ages.
This whole "plate is uber" issue doesn't take into account that DF uses a materials-based system. If you make plate arbitrarily and objectively that wonderful, then why not just forge a bunch of copper plate? Why develope steel at all? Or hunt for HFS metal?
Everything had it's strengths and weaknesses, and there were always a great many variables to consider, no matter who you were, or even how much money you had. That's why they are called "medieval", as opposed to "modern"--because weapon systems of the 1400's continued to be developed and improved, and will continue to be many years from now.
They weren't perfect, and we don't use them anymore. That's easy enough for anyone to understand, with or without a background in structural engineering.
Plate, itself, evolved over time. The design changed. Many times. Is that hard for anyone to understand?
Masterwork steel plate should be extremely good protection, should make the dwarf wearing it hard to stop on the battlefield. I'm all for that. Masterwork steel plate isn't easy to manufacture, and it should give appropriate benefits. But not unrealistic benefits, even against piercing weapons. Otherwise, you'd only ever need to forge a single suit of armour.
There's no good reason to make a bunch of ridiculous, non-fact-based guesses on what was what. If something works better for game balancing, and has a real benefit to gameplay, then go for it, but making an uber fantasy version of plate, just because, just makes the game simplistic, and a lot less interesting. Plate was better protection than maille, which was better than leather, which was better than nothing.
That's just not the whole entire argument. This isn't D&D, afterall, and I think DF should strive to be a little deeper than that.