I think the gathering professions are fine as are. It's nice that they added some bonus features; HoT(herbalism), +stam (mining), +crit (skinning). The only thing that needs changing on them is how many/where the nodes are and how quickly you level them. With all that blizzard has done you now often out level your gathering profession and end up having to go back to a grey area just to run around and level it.
As far as the crafting professions, they are good from lv 70-80, but irrelevant to all the other levels. Until you start crafting Northrend gear/enchants you are basically just making items to level the profession, not so that you can use them. I am leveling Engineering on my alt and so far the only useful items have been the first two goggles (by the time you can make the higher lv pair you are getting better loot drops) and target dummies. The bombs,explosive sheep, etc. I found the same thing to be true for Tailoring/BS/LW, the items you could make were always lagging behind your level progression.
On the other hand, once you got to Northrend crafted items, they are great for any toon that doesn't have lv 70 end game gear. And the enchants that a crafter can do to themselves are awesome. Bliz just need to retrofit some of those implementations.
You should be crafting items to use them, not just to up your crafting skill.