So on the concept of the "value" of heavy armor- I don't think it's as big a factor as some might think. Consider first, that any class that doesn't have access to heavy armor has at least some reason to invest in Dexterity.
You could built a pure melee Ranger, of course, but they do have a few skills and features that suggest you might want to invest in Dexterity. Indeed, if you are a pure archer, switch hitter, or stealth enthusiast, you can do without Strength entirely, due to the current game's design.
Some classes are built to reward you more and more for an investment in Dexterity; on a long enough timeline, the Barbarian gets more out of raising Dexterity than they would out of investing in armor.
Even a caster class can find value in having a decent initiative bonus.
But even if you invest in the Strength required to wear heavy armor, you've shouldered the financial burden, and are perfectly fine with the penalty to Stealth, the end result is, by endgame, you have an AC 1 higher than most characters. A Mage Armor using caster can gain the same benefit for the trivial use of a 1st-level spell slot. A Monk or Barbarian can even exceed the benefit granted by heavy armor.
This puts heavy armor in a strange place where it's most valuable at low levels, where you can't afford the best heavy armors, pulls ahead at medium levels, but at high levels has a small benefit (with a hindrance attached) or can even be left behind.
Now granted, there is the issue of "what if we're using point buy? Points saved on Dexterity can be spent elsewhere" or "what about ASI's? ASI's not spent on off stats can be used to gain feats!".
But it's worth noting that, regardless of what most tables do, point buy and Feats are actually options- options that the game's design supposedly doesn't even take into account (according to WotC themselves). And further, we see that when options like Multiclassing and Feats are on the table, it's not especially hard to acquire heavy armor if you do want it.
Even worse, racial options exist like the Tortle, who gain a natural AC of 17, almost as good as the best armor in the game, which, with the downfall of racial ability scores, means high AC is within anyone's reach, if they're ok with being a turtle man!
My takeaway here is twofold; if you are "budgeting" heavy armor for a new class, it's not actually worth very much, when compared to, say 1e/2e, as it currently exists.
Which, to me, means that if heavy armor is seriously meant to be a major draw for the classes intended to use it, it needs to be better than it currently is.