title is self-explanatory, but with a better in-depth analysis, there are very few necklaces that are legendary (Especially since it is near to completely impossible to get a legendary gold ebon necklace for the ebon armoury set as with many other sets out there), but if jewellery crafting was implemented, then people might be able to do better with crafting unique set combinations & coming up with new possible meta's to use in eso.
but putting it honestly though: what are the chances of ZOS implementing Jewellery Crafting into ESOTU???
I know what you di-Iddly did... (you would be wise not to do that again during a time when Suspicion in the gaming space is at an all time high.)
by not actually revealing real drop tables in the game for all items, you only prove what has been proven with proof of concept that you can/will manipulate item drop chances based on certain elements performed by the player.