[MENTION=83996]Lokiare[/MENTION], I'm going to attack your basic assumptions here.
First of all, a fighter with lighter armor should have a lower AC than a fighter with heavier armor, other things being equal. A high Dex can mitigate this to some extent, but if you want to play a class who is focused on weapons and armor and intentionally ignore one of its main benefits, especially when the system offers other ways to achieve your goals, doesn't make the system flawed. It's like when, in early 4e, a player would talk about his character concept- an archer fighter- and then freak out that the best choice wasn't actually the fighter class, but rather a ranger (probably).
Is the light-armor-big-weapon-fighter-class supported in any edition but 3e? Not AFAICS. Certainly, in 2e and earlier editions, heavy armor was always better than light armor- unless you were trying to swim! I suppose you could say that 3e supported this concept, or at least enabled it, but 3e would let you it-bash together virtually ANY concept once it had enough feats, prestige classes, base classes, racial levels, planar levels, other substitute levels, etc. You know, not just after the game was actually released but years after, once it had had time to mature and for lots of supplements to fill in lots of the weird gaps ("hey, do we have a way to apply Intelligence to initiative instead of Dexterity yet?").
4e didn't support this archetype either, at least not actively. All 4e fighters are pretty well expected to wear scale armor or better (unless there are some builds in weird places that I'm unfamiliar with).
Ahhh- but take the "fighter class" away and every edition can give you what you want, just as 4e can make that "archer fighter" as a ranger or rogue. Depending on the edition, you can play a barbarian; a ranger; a rogue; a bard; a prestige class or multiclass combination. You just have to accept that fighters are good at some of what you want, but there are classes that do it better. If you still want to play that type of fighter, fine, but you made a suboptimal choice. That means the result will be suboptimal, as well.
As to your defender wizard, I'm not even clear what that even means. Do you mean a frontline fighter who just happens to be a wizard? When has D&D ever supported that?? The closest I can think of pre-3e involves weird broken kits, and you still end up as a non-frontline combatant who gets cut to pieces in melee. In 3e, if you add enough feats and prestige classes, you can certainly do it- but you're hardly a wizard at all anymore by that time. And what's the difference between that and going fighter/mage in 5e?
I don't think your complaints hold water. Suboptimal choices ought to be suboptimal; there's no need to make crappy armor equal to good armor. That defeats the purpose of good armor- there's no reason to pay 600 gp for something that is no better than something that costs you 5 gp. Nor, do I think, should a wizard in melee be anywhere near as effective as a fighter. This isn't an issue of playstyle; it's an issue of balance. Why play a fighter at all if a wizard can stand in the front and throw fireballs?
It seems that your whole argument rests on the idea that every combination should be equally good. I simply disagree. A fighter with a dagger and leather armor should, in combat with an equal-level fighter, be seriously disadvantaged when the other guy has a bow, sword, shield and plate armor. A wizard in melee combat should be seriously disadvantaged against any fighter of comparable level.