We sorta kinda have an intermediate step now, but it isn't fully implemented.
You have your Cloths, Leathers, Chains and Plates
Cloth/Padded is the one that isn't well implemented if you think about it. Another way to think of this is the 'Rolemaster' approach. In that game, you have your soft leathers, rigid leathers, chains and plates.
So your Cloth/Soft Leathers would have a base protection of 1 (2 for torso), your rigid leathers would have 2 (4 for torso), Chains usually now have 3 (6 +/- for torso) and Plates have 4 (8 +/- for torso). Actually, there is a lot of variability in the chains and plates, but you get the idea.
The current values are fairly close to this, so introducing 'hard leather' boots and such would accomplish this, which is pretty much what the OP is getting at I think.