Well, why? Can't stuff be rare?
If there's anything the MMO history taught us is that, at least in the west and at least for items that are functional/important to play your role, people don't like a high degree of randomness.
Hard to obtain, even borderline impossible because of how much work/effort it takes? Debateable but more likely than not acceptable.
Huge amount of randomness with stuff that's completely out of your control? Usually not accepted.
Here earrings are bound behind:
A % chance to obtain a case
A % for that case to be normal or +1
A % chance for that case to obtain one of the earrings you want
A % for that earring to be NQ, +1 or +2 quality
A % for the stats on that earring to be close to the maximum amount
It's... quite a lot of randomness if you ask me, way too much and you can't do anything about it, it's just a lottery. You could be done in one day or not being done after 10 years, that's how it works, it's random.
The only degree of control we have atm is being able to buy an NQ Case.
They could implement an exchange system (similar to the reive capes ones), they could implement an Augment Refinement system (trade Sapphire and Earring for a re-roll on the stats), they could make so that when you open the case you have more chances (not 100%) for that earring to be of the current job instead of completely random.
I mean so many things they could do and that they've already done in the past.
But atm the Earring thing is uncontestably one of the less refined and more obnoxious part of what is otherwise what I'd dare say a pretty refreshing and well designed event.