Crafting
There is no benefit beyond the convenience in not having to alt when you want to craft.
If I remember correctly, there is actually a disadvantage in that a character can only have 2 disciplines active at one time. There is a fee for every time you drop one to activate another. There are gem store “additional crafting licenses,” but that only works to add up to 2 additional active disciplines, per character.
There is a fee for every time you drop one to activate another.
That fee is 50 silver every time you wish to change one crafting profession to another. So as to whether you are willing to spend that for the convenience of staying on one character is up to your in-game wallet.
The benefit is that you only need 1 recipe of something if all of your crafting is on one character. I’ve saved tons of gold and other currencies like crests doing this. Also. if you buy the crafting expander from the store, you can have 4 crafts active at once without spending any money.