Immersion,
socially incentivized content via shared struggle,
fresh content,
abstraction of game systems;
less focus on trivial, fluff details like menu-based content systems.
World PvP,
less overarching Quality-of-Life,
world content,
meaningful progression,
less itemization bloat,
longer retention rate due to content difficulty and length.
Socially incentivized server-based events (1.9 AQ War Effort),
tiered PvE progression;
Open-rank PvP Ladder,
Long, fun battlegrounds,
thematic integrity,
atmospheric immmersion (weather, night-time),
tiered complexity (ie. a balanced learning curve for noobs).
Lore integrity
Notable quest-based content (Sceptre of the Shifting Sands, Benediction, Rhok'delar, etc.)
Aspirational tiers of content (Naxx 40)
Realm community integrity (No CRZ)
More reason to travel
Immersive game mechanics: Pet Happiness, Ammo, Reagents, Spell-ranks
Complex character agency (Talent trees)
Diverse classes, no homogenization of purpose
Inconvenience adding to the adventure.
Non-linear PvE, modular progression
Non-linear dungeon content
Non-linear storylines and questing
Distributed population of players within the gameworld