The saying goes: Jack of all trades, Master of none....

So yes, people who have all crafts, or at least multiple crafts leveled, should and still will have a benefit: You can make your own mats, and have the flexibility to change crafts as the market changes etc. Also, the post didn't say that ALL skills would be class specific, just some.

But for those who choose to 'Master' one craft, there should also be a benefit. Also, I'm sorry but there should be a different feel to Cooking than to weaving. This plan is one way to do this, and I see nothing wrong with it.

Also, a while ago it was announced that once level caps are raised, you will only be able to fully level one craft. (And no, I'm not digging for this information now). But if this is in fact still the plan, it would only make sense to change crafting in this way.