Ok, here's what I think would be interesting:
- The skinned leather should retain the level of the mob/player it came from as well as the race.
 - The AC of the leathercrafted product should be dependent primarily upon the level of the skin used. The AC would then be modified slightly based on what it came from (like a seraph skin giving improved holy defense with disruption weakness as mentioned above.)
 - The level of the skin would determine the level of leathercraft required. For example, you could require 5% of leathercraft for every level of the skin, so 100% skill would be required to work with a lvl 20 skin.
 
And I sorta like the idea that leather armor could give a bonus to dodge, thanks to lighter weight/improved flexibility.
I've seen people say on chat that leathercraft's advantage should be its "quick to make" nature. I 
strongly disagree. If we were trying to recreate modern Chinese industry, then maybe, but as a leathercrafter I am dedicated to my craft -- I spend time on it; put effort into it to make something that will endure. I don't want to see leather armor go from mostly useless to a mass-produced, disposable piece of junk.
Similarly, I don't like the idea of reduced speed runing/enchanting on leather.