Living Story unlocked Rewards
It is unlikely this will be incorperated unless the living story itself is repeated and it is a recurring item.
The possibility to use it on all your characters as many times you want makes and item less unique and will likely upset the people who got something cause it is something unique.
Arise, ye farmers of all nations
Arise, opressed of Tyria!
Arise, opressed of Tyria!
I can see the less unique but as far only upsetting people that got it not so much.
The item would only be unlocked if you Achieved that achievement (The Dragon Bash Experience). A new player would still not have access to it, unless like you mentioned, the living world was to repeat, like SAB. The uniqueness would still be there and the pride of getting that item would still be there just on different character on that account.