First, regarding the leather armors. There's currently a problem that certain generated leather armors (such as rathound/pig ones) are generated from components of too high a quality. That is - you cannot find those components naturally occurring (if you disregard the messed up qualities in some shops, but that is being fixed) and yet they are used in generated loot to create these armors that are in a way more powerful than they should be.
Do you want to limit quality of leather armors from loot/shops to the level of leather we can get from monsters? That sounds really bad, i hope i misunderstood something. It feels unfair to limit quality of some components while not doing the same for others (like metal plates).
Yes, I do. And this is already the case with most components in crafting. But on the other hand I will also expand the variance and quality range of leathers available in the game, so this should not come as a nerf.
Currently, the generated leather armors are often made out of components that should not have that high of quality, e.g. you shouldn't be able to have Q100 pig leather armor as pigs simply don't drop leather that good. Nor should they since they are not high level monsters themselves. So pig leather armors will need to be restricted to the quality of the naturally occurring components, but on the other had new leather types will come in to fill that gap - either from further processing that leather type (e.g. reinforced pig leather) or as direct loot from new monsters.
Not all of these new leathers will be restricted to crafting-only (that is, they will appear in looted and sold armors as well), but the very best ones will be.
But, again, this has no bearing on the issue at hand which is how riot gear measures against other types of armor.