Machiavelli said:
I've always thought that the magical items, enchantments, and such are out of control in D&D. Classes, PrC's, templates, feats, skills, weapons, armor... these are flavorful, interesting concepts that progressively add to a player's abilities and power. Magic items... mostly aren't. You just have this... THING hanging around that for no apparent reason, and with no odd side-effects, arbitrarily improves you. Ok, so you have a metal band around your wrist and a vaguely sado-masochistic leather belt around your waist. Why the heck do these things mean that I can't seem to get my sword to HIT you despite my unerringly accurate blows and your pathetic attempts to move your squishy, vulnerable flesh out of the way, AND you can crush my head like a walnut in your pale, skinny fingers?! WHY??? Oh, right, just cuz the rulez sez so. THAT makes sense.
Rebuttal:
Those bracers, which are more than just metal bracelets, but instead are metal or leather pieces that strap to the forearm (either the inside or outside, depending on if you're a fencer or an archer), and provide a magical force protection, protection much like a chain shirt. Oh, and I think that belt's a Belt of Giant Strength, and so it uses magic. How would you apply a Bull's Strength via in-game reasoning?
Now, I'm done with the rebuttal, on to the OP's original point.
I really see no issue with the lack of heavy armor. I find that I don't enjoy characters in heavy armor, visually at least. I have, though, played a character that at first level acquired Plate Armor of the Deep. Previous to this, he wore a chain shirt, but after that, it was his signature, and since his dex was low enough, and the PAotD didn't penalize his swimming (not that he had any), it worked for him. This was my first (and only) Living City character.
Most characters I see in images usually are wearing Scale armor (a medium armor), for instance, Jozan, Regdar, Tordek, Alhandra, to name a few. That's the largest I see the iconics wear. The epic cleric (ELH) is wearing either Full or Half plate. The epic fighter, either Half or Banded. The epic Paladin, either Banded, or Half. All are probably wearing the mithral versions thereof. Heavy armor is not very dramatic. It slows you down, is difficult to move in, and obscures pretty much your entire form. It gives RPers very little to describe.
I have a character in Living Greyhawk who wears Scale Mail, and will probably never go below Medium armor, mainly because he has a horrible Dex and needs all the AC he can get. He's a marshal/bard (he's grabbing Armored Mage at 3rd level), and it totally fits his character. If your Players don't want to play the lumbering guy in Plate Mail, then don't force it. So what? If they're not having fun, then they shouldn't be playing.