Although I agree with you, I'd like to point out Blizzard killed off world PvP with pretty one feature. LFD... They added almost the lazy-boy feature of grinding dungeons solely to level a character and that sadly removes people from questing and "living" in the world. Personally, I'm a quest baby and originaly started with a Draenei, Exodar in pretty much all servers is populated mostly by NPC's...
! But, others aren't so keen on them if anything most people aren't and it's why other quests in vanilla were revamped (to where there's not even group quests), and prior to that group quests were for a better word, removed...
Granted that heirlooms has also added to this because more experience at a faster rate means skipping zones altogether and less time in the leveling process. It's only when heirlooms miss the cupse of the levels say 85-90 does the leveling process be normal and in that example very long, therefore a wider opportunity for world PvP to come (also not to mention the tons of people leveling to be max level anyway haha), but still...
You can't really blame certain points of frustration, or people joining the game at different times so some nostalgic qualities are missing from that player. It's a bit of a grey area, considering this MMORPG along has had nearly 3000 days worth of live-server time! Excluding so many PTR's and Beta's ^_^. You also have to remember Blizzard did cater geneously for casual gamers compared to potentially Vanilla and TBC just because the genre was pretty young, the franchise's name in this genre not so well-known as it is now ^_^!