I gave a bit of thought as to what the developers intended in terms of the rarity of the XII STF sets as well as the reality as a player. I think the best change would be to satisfy the player base by making all the elite gear obtainable after reaching a fixed goal rather than a good dice roll while maintaining the intention of making the gear difficult to get.
I think the easiest implementation is this:
The developers designed the gear to drop at an expected value of M STFs played. I propose that after you reach N elite STFs, you earn an accolade for that STF. You also earn another accolade for 2*N. This number N can be chosen so the player is still receiving the gear at the previous expected value M, which means that the number of missions played for the average player before getting the gear will not change.
Each accolade gives the elite tech drop that occurs randomly. That way you will never have an unlucky player who plays a mission two thousand times without ever seeing that tech drop, but it is still almost as rare as it was before.
Keep in mind that this accolade would be based upon completing a specific elite mission N times. It would not require any new currency, could be adjusted so that the rarity is the same as it is now, and hopefully would satisfy both the intentions of the developers and the expectations of the players.
From a player standpoint, it would be a lot more satisfying to know, for instance, that if we complete The Cure ground on elite N times (even if N is a rather high number) we are guaranteed to get the gear.