Recipes like this, the various alchemy cauldrons and the like really should increase in availability as the expansion goes on. Having the recipes being rare at the start of the expansion is fine as it helps drive engagement but as the expansion wears on the drop rate should increase to help drive down the costs of crafting the items and to make recrafts much easier.
As far as I know there a whole two people on my server group who actually have the lariat crafting recipe (and one of those is based on the recipe showing up in the AH earlier this year - it could have been taken off the server via a transfer). I have been killing the primal storm rares for months on end and still I have never seen it drop for myself or anyone else with me at the time.
It took weeks for me to get the regular potion cauldron from Vault at the start of the expansion and despite clearing the current raid once or twice a week it still took me until just a few weeks ago to get the Potion of Ultimate Power recipe. The complete lack of Potion of Ultimate Power recipe dropping for so long really puts my raid team at a disadvantage compared to other raid teams who got lucky and got the recipe to drop at the start of the expansion.
The Ring-Bound Hourglass recipe is yet another recipe which is way rarer than it should be - as far as I know my jewelcrafter is the only toon on my server cluster that has the recipe and I only got it a few months ago.