This can't be a real thread.. why would you ever remove them?
yes they would server no purpose
no i think they may still have their uses
I think they don't really have a purpose, but is it really necessary to remove them?
The best is to remove any form of leveling herbalism, mining, or disenchanting.
Inscription already has the ability to transfer inks. So, the best solution is to allow any level character to pick/mine/disenchant any item they acquire. If they need ghost iron, and they are level 12 toon, then there should simply be a NPC that will trade them copper for ghost iron. May be expensive to trade up, but so be it.
Lower level toons would rarely be able to farm for high level materials, so there still wouldn't be any issues.
I am also not a fan of the simple items put in for blacksmiths. Remove them, let them farm ghost iron, exchange for copper with NPC and voila.
I think implementing a system like the cooking levelling would work best (Obviously not so dead easy). So basically you can level up your Black Smithing with just the MOP ores 1 - 600. If you want however, you can use old world Mats. That leaves everything intact, but for players rerolling profs less pain.