They have already stated numerous times in interviews and the Live Letter that the intent is to allow people to be able to craft in one or a few classes without being forced to level all of them. They have not said a single thing about any intent to restrict crafters. I don't know why we are still having this kind of discussion.
In short: Specialist = casual crafters can pick 3 classes to not suck in, not that hardcore crafters can only access recipes from 3 classes.