What makes for good crafting?

Alverant

I was going to post in LFGame about an MMO with a good crafting element but then I realized I would have to define what I thought a "good crafting element" was and I couldn't come up with one. My MMORPG experience is long but limited. I've seriously played 3 different games one after the other.

Earth and Beyond

City of Heroes

Star Trek Online

I liked the crafting scheme in the first one except no one character class could go from raw materials to finished product (I guess it was in there for game balancing). City of Heroes depended on too much on random drops that getting a rare item was cause to celebrate but I don't think a good crafting system should depend so much on luck. In STO crafting isn't that great IMO and seems to depend on players playing real money for components. Or maybe I just don't fully understand their system. In any case what you can build isn't as great as what you can buy most of the time (and thanks to random drops you can find some stuff cheap).

So what do other people think what makes/breaks a crafting system? I'm not looking for game suggestions just things I should watch for.

Thanks!