Making an alt, period, is pointless in basically every circumstance. Crafting alts would be a completely bad idea overall. If you do it all on one character, you will get a higher physical level and be able to repair your own stuff.
The only reason I could see in making 2 or more characters are the following:
-Having a DoM and a DoW class, stats are hard to change drastically as you get higher, this would let you play both classes more easily without having to change out stats completely.
-RP reasons, you like having a Gladiators tank that can do Armorsmithing. Or you like having a Conjurer that only does Botany or Fishes. It is up to you, but isn't really my cup of tea.
-More inventory space.
Beyond that, creating an alt is simply a poor choice for your characters development and advancement in the game.
Edited, Jan 19th 2011 3:49pm by MattVid6