The problem with this is that WoW has been going for 16 years. The player character has made a name for themselves in that time. In Vanilla/BC we were "adventurers", random nobodies getting stuff done. Wrath/Cata we were grunts, recognized but still there just to do our jobs. MoP we had earned responsibilities and were notable. We served as lieutenants to people like Nazgrim and Admiral Taylor. In WoD, we became their equals. Come Legion we surpassed them, becoming one of the Greats of our classes, up there with names like Tirion, Rexxar, and Valeera. BfA we became a Chosen One, though we were still beholden to the will of our factions.
It's just a natural progression to keep the story going. If Blizz was gonna keep us as random adventurers they would have had to change direction all the way back in Wrath.