Originally Posted by
Eurhetemec
They intended to when they designed WoW. The original manual has references to it, to taking over zones, and to siege weapons in the open world. But WoW's PvP was severely underdeveloped when the game launched, and when they did get somewhere, they implemented the BG system, which was pretty cautious (and similar to the lower-level PvP systems of other games). Then in TBC and WotLK they experimented very lightly with these systems. You could sorta-kinda "take over" some zones in TBC, but all it did was give a bonus, except in Nagrand, where you controlled a small town, IIRC, and in WotLK they had Lake Wintergrasp, for open-world PvP with siege stuff, but it was pretty limited and linear. Then they sort of gave up, and whilst they had the odd PvP-related system or area in most (all?) expansions since, they never went back to that idea. I think it's probably too late now. It doesn't really work with the level treadmill anyway, because each expansion you'd change the zones you were fighting over. They should probably have implemented a couple of "frontier" areas like Dark Age of Camelot's frontier (one on each continent), which did seem to something they were thinking about, but oh well.
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I think this is a bit misleading. When WoW was being developed, PvP was represented as a priority and important, and initially, PvP-enabled realms were significantly more popular than PvE-only ones (I think this has since changed).
WoW released without much in the way of PvP systems, but they planned significant ones, as you can see in the original manual and if you were on the forums around then this got discussed a lot. The BG system they eventually implemented was a sort of "stop-gap", not intended to be the "final form" of WoW PvP. We were promised sieges, capturing zones, and so on.
But like the Boyfriend meme, WoW's head turned from a game supporting both PvE and PvP strongly and as part of the world, to a game which was primarily PvE, and had PvP as this entirely optional and entirely instanced activity. A lot of this comes down to Tom Chilton, who was in charge of PvP. He was extremely keen on the idea of "fair" PvP, and eSports (even before that was really a thing), and world-PvP is inherently never entirely fair and certainly not an eSport. So he brought in BGs, which people saw as a stopgap for PvP, and then Arenas, which had a mixed reception - I was for them at the time, because the PvP in them was intense and skillful and WoW's PvP worked really well in small group combat (or 1v1 or 1v2 or the like).
Which is another point. WoW's skill design was bad for mass-PvP. To work well with mass-PvP, you need a certain design of skills, which means stuff that's simple, doesn't interact in a complex way with enemies, and doesn't bog stuff down. You also need solid multi-target CC and so on (this is shown by various games, but particularly Dark Age of Camelot). WoW's combat just sort of devolved into a grey paste when enough people were in a fight. Not only did it get laggy AF, but all your precise, cool, move-countermove abilities became largely meaningless. So the designers wanted mass-PvP, but they didn't think about that when designing skills (and it's clear this was an error, because even in say Alterac Valley this "grey paste" effect happened).
Anyway, Blizzard didn't give up straight away. They did try to make most of their ideas work in the small scale, and kept trying different things, but none of it really stuck, and PvE stayed popular and what WoW was known for, and something it was clearly better at than other games (which was not the case with PvP when more than about 6 people were involved, 7-10 it's good but other games were as good - Warhammer Online, for example, 11+ WoW was pretty bad - I mean directly involved in a single combat not just "in the battleground" here), so PvE eventually won out in a more solid way.