Well, that thought just hit me.
Its kinda obvious that Azerite, just like Artifact Power, is the one-addon feature, so it not gonna last for more than BFA.
We stopped using Artifacts and AP in Legion to cleanse the wound left by Sargeras.
So what are the lore reasons for us to stop using Azerite in our gear?
The answer is simple - Azerite is the conductor for the Old God(s) will. Through it they manipulate us all.
Im pretty sure by the end of BFA, when we will fight the Final Boss of this expansion, we gonna destroy all azerite power we gathered to free themselves from the Old God(s) influence.