"Because I say so" isn't a discussion. If you don't like it, say why you don't like it. Just saying "Nonono" doesn't help anyone.
It's just my opinion on the question; there was no good answer for me to vote with. (I've seen a lot of polls that do this lately; they try to put words in your mouth instead of leaving a simple yes/no option.) If the question had been, "Is heavy armor underpowered in the playtest/4e/whatever specific edition", I'd have answered differently- post 2e, it is indeed underpowered. But that's not the question.
Wouldn't it suck to be a pc and crit the BBEG only to not get a crit because he's in plate mail? (Plate-and-mail if you want to be pedantic about it.

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You don't have to rub it in, Jester, the polls are in, it's fine.
I posted before reading the thread or looking at the poll results; apologies if I came across too strong.
It's just the more I think about my old AD&D group with fullplate wearing paladins, and how they'd walk around and never take any damage except for crits, eventually the DM rolling a huge # of rolls just to check for 20s. Kind sucks.
The only viable solution in here I've seen that keeps heavy armor strictly better than light armor, is keeping the Dex bonus up, but that means having 25 AC. Can the game handle that?
Or are you one who thinks Heavy armor should be numerically worse than light armor. When you factor in all the rules of the game, even with plate getting 1/2 dex, that means it'll be around +1 or +2 AC over the studded leather guy.
Okay, speaking to the actual issue that you seem to be addressing- the heavy armor issue- here are a couple of my thoughts.
-Keep dex bonus to AC with heavy armor. Lightly armored creatures should generally have lower ACs than heavily armored creatures; it kind of weirds me out in 3e and later when the rogue has a better AC than the fighter. IMHO the difference is that light armor should favor other types of playstyle and pc other than the front-line guy. (The lightly armored front-line guy should, IMHO, be straight-up less capable than the heavy tank when it comes to avoiding damage via high AC. I'm okay with other methods of light armor defense to compensate, but they should be
different.) Even with this, I don't necessarily see a max potential AC of 25 as game-breaking.
-As an adjunct to this, I want the elimination of expected wealth by level so that armor's cost matters beyond first level. Also, I favor 4e's "natural 20 that would miss is a hit but not a crit rule.
-As I stated, I don't favor anything that stops the pcs from having a spectacular bacon-saved-from-the-fire moment by critting a bad guy just because he's wearing heavy armor. I favor effects that increase the number of crits in a game, not decrease them, and am a huge fan of "colorful" critical hits (you know, "Blood in eyes" or "limb hacked off" or what have you). (Then again, I also prefer a fairly lethal game.)
-We can eliminate the current penalties for heavy armor and just replace them with a speed penalty and a note that the dm should consider handing out disadvantage for the armor in appropriate circumstances.