We have the division between "heavy" and "light" armor, previously also medium armor. And think about this a little: the cheapest heavy armor you can find is a full plate suit, and it's very cheap. It's a full plate armor, making i out of some indestructible fantasy material is the only thing that can make it better, and that's how it's done. Light armor makes little sense, too, actually it only makes sense in the early levels. But then, look at this guy http://newwars.files.wordpress.com/2010/03/ancient_sasanid_cataphract_uther_oxford_2003_06_21.jpg that is a reconstruction of a cataphract, the stuff he is wearing would be called "light armor" in TES, and that's just stupid. Chainmail is heavier than full plate, just less restricting.
The division between the armor types, another thing is balance. In real life, heavy armor was EXPENSIVE, only the elite could afford full armor suits. But in TES you can just crawl out of the prison and buy yourself one. And that's why I think the current armor system should be abolished. When we have light and heavy armor skills, the classes need to be balanced, meaning we will have ridiculously cheap heavy armor and super-protective armor that weighs nothing(OK, because it's a fantasy world the super light armor is no problem).
Here's what I think of it: Instead of having equipment from 2(or 3) classes, there is only weight and how restrictive armor is. Because armor skill doesn't make sense in the first place, agility and athletics should be what makes armor movement more easy. That would be great for roleplay, you have the choice of what to do based on what you need. A normal adventurer wouldn't need more than a chest armor and some good boots, maybe. But if you want to be a tank warrior, you can get yourself some fully covering heavy armor. The current system makes it so that it's no good option not to use armor, and i you do, you better carry a full suit, just minimal penalties!
Also, there are minor things like armor naming that are off, it doesn't matter, but there's no reason not to fix it. A cuirass is a hard briastplate, greaves are armor for the lower legs, the "greaves" in TES are really chausses.