I've always tried to avoid having a crafting profession on any of my toons.
Sometimes when I've rolled a new one, I've started them out with something I thought might be useful. But in the end I've usually ended up switching it for a second gathering prof.
I've just never really seen the point. Most of the end-game gear is better or equal to the crafted items. And it's effectively easier to get, because it either comes from rep rewards or from instances which other people will also be doing, and also provide additional drops and benefits.
I think part of the problem is that the lower level items produced by crafters are just totally pointless now. Essentially you're going to be grinding out the lower levels, and spending extortionate amounts of gold leveling your prof, just to reach the higher levels where things start to become useful again.
Having said that, I've levelled my Engineering on my new Pally. To the point where I can now use the AH in Dalaran. Now it's cost me around 800-1000g to reach that point. But I've also made some ofthat back by selling some of the crafted mats.
I also have maxed mining skill, but I try never to use my own mats. What I do instead is buyout any underpriced ores / bars on the AH, and then post mine at just under the price of the next highest.
This isn't always posible, obviously, if the prices are stable, and there's lots of an item available, sometimes it's just more sensible to use my stuff, rather than paying the posting fee, and letting the AH take its cut too.
But anyway, the point is realy the crafting. Using engineering as an example:
Between certain level ranges, the lower level engineering items are used in higher level items. For example, blasting powders are used in many items, but the powders themselves are crafted at a much lower level than the items they are created for. This makes sense.
But once you pass the next level of the profession (e.g. Moving up to Grandmaster) all the stuff you've made and learned before that level is wasted. The items are useless to you, and with the excpetion of a few crafted materials they're worthless on the AH and with vendors.
Now, in my opinion, what Blizz need to do is allow items to be recycled (this would especially fit in with the engineering prof). Essentially this is the same as dis-enchanting, where materials are extracted from a crafted item.
You wouldn't get back everything that you put into it. But you'd at least salvage some of the mats to re-use or re-sell.
Or, the lower level items should be useable or transmuteable into higher level items. Think of the skinning Prof. Every skin can be transmuted into a higher version. It might need 10 of a certain skin to make 1 of the next level, but so what? If they don't get used, they'll eventually just get vendor'd.
With everyone who's trying to level a profession needing to make exactly the same items just for the sake of levelling, they're bound to be worthless to others, or have little value on the AH.
I know Blizz like their money-pits, but in the case of professions, they're going to be making enough back anyway. Do they really need to have us vendoring all of that crap?
With all that said, I'll be sticking with my engineering, although I won't be pushing hard to max it. It was more for the AH and the funnily-useful stuff like portable mailboxes and repair bots, rather than for epics.