To be honest, because its totally unnecessary at the moment.
Back in Cata, the only source of end-game gear was the Raid. PERIOD.
But a 10 boss raid (on average) can only have so much loot-table.
In fact, if you compare the loot tables of modern bosses with old bosses… you can see the difference : They were massive back then.
What this implied is that in WotlK it was almost impossible to loot what you needed. And secondary stats used to be a big deal back then. Today, primary stat is >>>> anything else. So ilvl increase will 99% of the times be an upgrade. It wasent the case back then.
So blizzard tried to solve that issue with reforging. It reduced the size of the loot tables, but gave you reforging.
Does reforging have a place in today’s wow? Maybe yes, maybe not.
From a fun perspective maybe. From a systemic perspective? I dont think so. Raids are not the only source of end-game gear anymore. And secondary stats dont have the importance they used to have.
To add to this as well :
Class balance. Classes are better tuned today. In the sense that 99% of specs find some value in any of the 4 secondary stats. Back then, it was the other way around. There were classes where specific stats were a 0 upgrade.