Yeah I really don’t see why something deterministic was never considered for this. They could have kept the full quest item drop as a rare “surprise!” moment while also adding guaranteed drops that eventually let you create the quest item.
Cracked Titan Gem Fragment - Combine with 23 other fragments to create a Cracked Titan Gem.
Drop them based on difficulty, with results being additive over the course of the week starting with a max 4 on Mythic to a min 1 on LFR. 6 Mythic Sark kills required to guarantee, or 8 Heroic, 12 normal, 24 LFR. (Yeah I realize this would seem “unfair” to LFR-only raiders but there is no way to make everyone happy and it gives incentive to maybe find friends to do normal and speed it up.)
My evoker already has 5 Heroic kills and many other people have over 8, so something like this would have made a lot of people pretty happy while maintaining the surprise off-chance that someone just loots the Gem natively without having to grind.