Armour has a downside as well, being bulky it lowers you chance at agility checks, and with dodge rolls (ie, your defensive roll to avoid being hit). So while you will take less damage per hit, you will be hit more often. Armour can also be bypassed by "armour piercing" attacks, such as gunpowder, a crossbow or the like.
This means you may wish to change your armouring based upon the conflict. If you are fighting a swarm of nimble goblins with small knives and clubs, then heavy armour is a good idea. Even if they hit you more, their feeble blows will almost never bypass your armour.
Compare that to fighting a giant, the lumbering brute will hit with such force and damage that the armour will not do much (if any) good..but if you are nimble and quick you have a good shot at never having a single blow land against you.
Now originally I had custom listing of armours each with their own (arbitrary) DR reduction scores versus pierce, blunt and slash attacks as well as their own dodge modifiers and the like.
That irritated me, as historical armours were built to counter historical arms and equipment. When faced with new dangers and new biology's of the wearers, armour could look very different. If you aren't primarily concerned with stopping arrows but troll claws, how would the armour differ? What about if your vital organs are in your lower gut and nothing is really in your upper torso?
For this reason I used a similar system to weapon tags. Armour is selected as a type (light, mail and plate) and then tags with their modifiers to the weapons stats are used.
So light armour has a DR of 1 as a base and a dodge modifier of 0. If the armour is also
A listing how historical armours would break down is still included.
Why is this good?
In terms of the concept of avoid being hit VS ignore damage is a good example of having a choice and no "right" answer, only better situational answers.
The benefit of the tag system is that it removes the need to memorize the abilities of a myriad of different armour types. You can also limit it to "tag-less" if you want to trim the rules down more to something simple and easy to remember.
Why is this bad?
Sometimes you WANT a holy grail of armour, the worlds best system that you want everyone to strive for (such as power armour in most sci-fi games), or you simply enjoy having lists and tables of armour types (nostalgia is a powerful thing, I admit it influences me quite often).