As far as I can tell, do you not make more money by farming what you need if you are say a miner, selling the ore, and then when you want something from blacksmithing, simply commission someone to make it for you, you will have the mats? I mean the tip you give them wouldn't compare to the amount the raw mats you've gathered sell for, so there's no real money in crafting, is there? Unless you get uberlucky and get a very rare drop, or can afford to buyone from the ah, in which case you need loads of cash, catch 22.
Basically, what's the point of skilling up crafting, when you could simply gather, sell the mats, and commission someone when you want something crafted?