• It's a prominent aspect of most cultures, including Japan (getting hammered is such a huge element to most anime, both in terms of a right of passage, and as a humorous trope).
  • An enormous amount of the RP in the game is bar-centric - either in terms of player-run establishments, or just milling around in the watering holes in the cities.
  • Being drunk in MMORPGs is not a negative experience, nor is it a gateway to bad behavior out of game. I mean, first of all, we're doing much worse things to people, animals, etc. with our weapons. Second, most adults consume alcohol IRL, so I'm not sure how it could 'lead anyone down a dark path.' Third, it can produce hilarious results when handled correctly (screen going fuzzy/blurred/wavy; slurred speech; difficulty in character movement, etc.).
  • It can actually have in-game mechanical uses - such as a boss that blows up a keg mid-fight, suddenly rendering your character inebriated and in need of a quick cleanse.
  • It's immersive for the kind of experience that SE is clearly attempting to otherwise push - high-end, player-driven socialization.