Meh, I can see both sides of the argument.

Pro: uses less inventory, less time spent transferring items
Con: encourages hoarding of materia, really not needed with good inventory management

I know the last con will fire some people up but I'm finishing my last three crafting jobs to 50 right now and honestly, with all my gear and mats for all jobs I have about 180 spots open between my character (50 spots always) and my retainers. It would be nice, but it won't cause any problems one way or the other unless someone wants to try and use the ridiculous "use of resources" argument which is pretty much a FFXIV version of the "slippery slope."