lemme see here…
-professions are viable from level 1 to max
-immersiveness due to rpg features like requiring quivers and arrows/bullets for hunters, learn poison making, getting the materials and making/applying those poisons for rogue weapons, candles for healers, portal stones for mages, ankhs for shaman, seeds for druids
-cc in dungeons being a must, where everyone takes part in pulls before they happen, planning and strategizing, then applying that in the form of ccs.
-encouraging exploration/adventuring, actually knowing where everything is in the game world (many retail players have no idea where the entrances to dungeons / raids are because they just queue for them from home cities)
-gear upgrades actually feel really good. blues are amazing and epics are wow!!!
-freedom of being able to mix and match talents from all three talent trees. plus getting alot more talent points, more often. this has so many variations that to this day, it hasnt been fully theorycrafted
-difficult levels for meaningful content requires/encourages help from others, building community. feels more like a mmo instead of a lobby game.