I get it, people couldn't get it then during the timed collab and that sucks, but by that same logic, all ff15, dragon quest, yokai, etc. collabs should come to the store.
The only way FF14 can remedy this problem is making a slightly different version of the animation to bring to the store, this also includes any and all past collab items.
If we take a step further, if we're talking about timed exclusive items, bring back slightly different versions of the past seasonal feast rewards to the store because people will be sure to buy those in droves.