Nope, world pvp existed because the mindset of players was different at the time. The people playing at that time came from games where you had alot of open world pvp or they simply did not play any mmorpg before and just WANTED to whack the other faction wherever they found them. You also had no bgs, thats true, but there was still alot of open world pvp after they introduced bgs.
The biggest problem with the player right now is the "no reward = no thanks" mentality. Simply doing something because its fun, even if there is no point to it, this just does not work for people anymore after 10 years of wow and being conditioned into waiting in your main city until the queue pops up and only ever leaving that city when you might need to farm some minerals or herbs or do some dailies. Thats what has happened over the last few expansions. You dont see people out in the open world anymore and naturally there is next to no open world fighting going on anymore.
And btw, world pvp rarely ever means zerg vs zerg. Those massive battles happened, but they were nothing that regularly happened. World pvp usually was smaller scale. This wrong perception of world pvp being massive battles is one of the problems that might explain why Blizzard has no clue on how to set up something that people would like. The fun and dynamic nature of world pvp resulted from having smaller groups of players gather up over time and fight others over a rather large area in a zone and only loosely working together. This is where wow pvp also has most of its strengths. Once there are too many players, all of that goes away and ends up in a big laggy mess where the group with the most AOE wins. And this has always been shit. You can see it right now in the abomination of TM vs SS aswell as in Ashran. Everything that happens near the zerg vs zerg is completely useless and feels pointless.
The only fights that are interesting are the scattered fights away from the action there. Thats the only reason I actually still go into Ashran, because there you sometimes get fights that are fun, with people adding in the middle of the fight, changing the whole direction of how the fight is going down, then all of a sudden you get 1-2 reinforcements from somewhere helping you out close before death. And all of that has nothing to do with 60 ppl standing in one spot spamming AOE dmg and heals. I still hope that someday Blizzard realizes this, but right now I dont think this will actually ever happen...
There are many ppl who may remember some big fights back in the days and those ppl are probably who just remember those fights and stored them in their memory as "this was world pvp" because these were the only fights they really were part of. The players who were pvping ALOT back then usually dont see these zergfests as the real pvp, because it was a rare sight and usually ended up crashing the server anyways and while fun for a while, the real action usually happened between those events by attacking people on the roads, creating kill zones with small groups infront of Blackrock mountain where you could kill off entire raid groups that trickled into the entrance, only to result in very fun battles over time. Or the chillwind flight point at the edge of eastern plaguelands near Andorhal where we had so many fun fights. And these fights at that flight point were often resulting in skirmishes that carried on over down to Southshore vs Tarren mill, because alliance people would not fly into Chillwind but rather just to Southshore to not get picked off one by one and instead ride all the way up to Chillwind, and after they beat us with a big army there, they would come down to Tarren Mill and mayhem would sometimes break out all over the zone, sometimes lasting for hours, sometimes just for a few fights.
THAT _WAS_ WORLD PVP and I am sad to see that something like this will probably never happen in this game again just because ppl dont move a finger anymore if it doesnt give them a reward or lousy achievement