Perhaps I'm not the norm, but once recipes weren't locked behind specialization, the only thing I found useful about it was the bonuses the soul-stone gave me. On the other hand, getting those soul stones was essentially free.

Perhaps Specialization should be more like Jobs in the DoW classes: you need some but not much of another (crafting) class to become the "craft Job", it changes what skills you can cross-class, and it provides powerful abilities not available in any other job or class. Might be more interesting. And since you could always change to, say, regular LWR Class instead of Specialist Leatherworker Job (just as WHM can always run as CNJ is they want) there'd by no downside. And there'd be no need to a limit on the number of Crafter Jobs you could have.

And it might be fun. Skills and therefore rotations might be different for each crafting "Job," and inevitably some jobs would find it easier to do high-level crafts than some others. That's not a bad thing: it means good sproduced by those Specialists might sell at a premium, rewarding those who master the more difficult Craft Jobs.