During my definition of World PvP, I explained that PvP in an MMORPG is inherently unfair, and World PvP is simply a mindset. It isn't knowing how to attack, but when, and for what purpose. World PvP is less restricted, and involves nudging a situation in your favor.
While WoW's PvP isn't the cream of the crop, it makes for an interesting case study since the capacity to engage in "world pvp" hasn't changed, yet the popularity of it has. WoW helps illustrate why World PvP is a presumption outside of the game mechanics.
Some of the best moments of leveling a WoW toon involve situations where players fight other players for access to resources. These resources are almost always quest mobs. A high level character "ganking" lowbies for the perverse thrill of exercising power is not world PvP, and actually leaves a bad taste in the mouth of the inexperienced. But that is a problem with game rules, not world PvP.
A brief history of PvP in WoW:
No honor system. Many people questing. Many people, including lowbies, engaging in open world town raids for the novelty of it. No lasting consequences.
Spontaneous Horde raid on Menethil Harbor.World bosses introduced. Large scale fights to obtain boss loot. Scouting of enemy faction becomes paramount to knowing when to engage boss.Old Honor system, but no Battlegrounds. Many fights between Southshore and Tarren Mill. Fighting to mutually gain Honor.Battlegrounds. Much World PvP stomped out since Honor is easier to get in BGs. Without huge gear discrepancies yet, small pockets of world PvP still seen in Plaguelands. Blackrock Mountain has much PvP fighting over dungeon and raid access.Blizzard creates "outdoor PvP objectives" in Eastern Plaguelands and Silithus, and iterates on them in Burning Crusade. These largely flop. Massive gear discrepancies and prevalence of BGs shatter world PvP expectation. Minor fighting around raid portals.End of Vanilla saw bored raiders running 5-man PvP excursions while waiting for Arenas and BC. Ad hoc and arranged group fights while roaming.Arenas are introduced in Burning Crusade to the lauding of "fair and balanced" PvP folks. Resilience is added as a gear attribute. "PvP" is now an official route of character progression, and thus everyone sits in instances to optimize their gear acquisition. World PvP is a dirty word equated to ganking.Isle of Quel'Danas is added at the end of Burning Crusade to house Sunwell and a fresh batch of chores. This popularizes World PvP in WoW again. Players form parties for protection and fighting; they expect combat while questing. Isle of Quel'Danas implements a common model for World PvP that I will discuss later.Achievement system is added; reward to kill world leaders is introduced. Cities are in faction-owned zones, and thus combat is opt-in. These raids are not very disruptive to the empty towns.Wintergrasp experimentation with zone PvP with raid access reward. Like AV, Wintergrasp is just a larger Battleground. Vault of Archavon predictably and regularly changes hands between Alliance and Horde. World PvP is dead throughout Wrath, but accessibility is through the roof.Blizzard repeats success of Isle of Quel'Danas with Tol Barad at beginning of Cataclysm. World PvP makes a slight comeback. But people quickly get their reputation rewards and leave.
It is fascinating to see interest in world PvP ebb and flow as Blizzard tweaks PvP progression rewards. WoW is very elder game heavy, and thus all the resource warfare is at max level: quest access, raid access, & tradeskill material access. Cataclysm seems to have eliminated many contested quests for Horde and Alliance, so any PvP experienced while leveling is ganking or in a Battleground instance.
I definitely believe there are players in WoW who enjoy world PvP very much, and they would engage in that type of play more often if the rewards were not stacked against them. In the current game, once players gain all the reputation or gear they need from Tol Barad, there is little reason to go back. No other location in WoW comes with the expectation of PvP, and thus there is no world PvP outside of TB.
Some of the comments on my Definition post called into question "influencing the world". While not necessary for world PvP (illustrated with WoW's world PvP: no one would say they hold influence over that world), it is a strong motivator and part of Risk & Consequences that change the emotions conjured by the game, but not the game itself. I hope to expound this soon.