That's pretty incorrect. You can craft normal raid level gear for example a blacksmithing body
http://www.wowhead.com/spell=126852
or a cloth body
http://www.wowhead.com/spell=125558
Every patch there is epic gear that can be crafted that is the same level as the current normal raid gear. Every craft in WoW has a use. In addition to making some lesser quality gear thats not quit raid level from cheaper mats.
The crafts in wow are used throughout a whole expansion, every time a new raid tier comes out they can learn new plans for gear.
Enchanting - Lets you Enchant/Disenchant gear
Tairloring - Lets you make cloth gear
Blacksmithing - Lets you make Plate gear and, make belt buckels to add slots to belt
Leatherworking - Lets you make leather and mail gear, and leg enchants
jewelcraft - lets you cut gems
Alchemy - lets you make potions and flasks