Originally Posted by
Jastall
Well being fair, the first two bosses, Hellfire Council and Kilrogg could easily have been Iron Horde bosses with little but a palette swap, and may have been conceived that way originally even, hell I wouldn't be surprised if several bosses from the upper Citadel (Socrethar and Tyrant, possibly Gorefiend as well) were originally slated for the canceled Sharrath raid and they mashed the two together to create HFC after veering off from the premise mid-xpack.
But endbosses being a bit of a surprise was more the norm than not if you ask me. Who thought we would fight Kil'jaeden in the Sunwell during an xpack about Outland? If Blizzard didn't outright tell us, who could really have planned Garrosh would be the endboss when Mists began? Archimonde is obviously far removed from the Iron Horde premise of course, but Legion ended with us beating up a previously unknown nascent Titan instead of a demon lord or Sargeras himself. BfA was ostensibly about the faction war, but the factions are already teaming up (except for nasty eeevil Sylvanas) and we were outright told we would know who the final boss of the xpack is when we finish the raid where N'zoth gets released which kind of narrows down our options, doesn't it?