What do the colors mean for crafting

1) You can buy or craft more pouches or boxes with various storage sizes and properties (for instance, armorsmiths can craft a 'safe' box that holds 8 items that will not be sorted with compact or moved to collections unless you do so manually).

2) You can also unlock extra pouch/box "slots", via the in-game store.

(At work; can't check the site/wiki to link URLs.)

So two things:

First, every character can learn every crafting discipline. You won't even lose progress. The catch is that you can only have two active discipline at once (as in, can craft things with them), and it costs money to switch between them, based on how highly skilled a discipline you're switching into. (If you switch in to a discipline you have no experience in, it's free!)

Second, most untradable items are, in fact, account bound, so you can freely store them in your bank and remove them. I assume the actual Legendary Weapons will bind to a character, but the materials can be passed around willy nilly.

But Crafting in Guildwars 2 is very much its own part of the game. Crafted gear is equal to gear earned from any other number of options, and is not inherently better. The only real "perk", if you want to call it that, comes from convenience.