Consider the name Warcraft. We've not seen much of it in vanilla or TBC. Warring between alliance and horde, aside from battlegrounds, there's not enough going on.
What if Blizzard never launched TBC but instead released an expansion that was built on the base they laid in vanilla? Foundations like neutral pvp zone, battlegrounds, a chat channel dubbed "LocalDefense" (I had to sign in as I was unsure of the way the channel's name was), factions and other things.