Aside from the well-played-out "what is a sport [in the traditional sense]" arguments, there is the point of worldwide participation. While StarCraft is immensely popular around the world, the professional competitors are centred primarily in South Korea, with lesser but still respectable teams and leagues in China and the United States. So its reach as a professional, um, recreation is not as widespread as other acceptable (but not contested) activities like billiards or chess or other board games. I believe among the criteria for eligibility are a single international governing entity and splitting the sport into different events. For computer gaming, not much of the former, and the latter, well, multiple game modes and rule-sets, I suppose. And with quite a handful of online games conducting tournaments and offering prize money, one should imagine some sorts of regulatory bodies emerge.
By Limxzero (5329)
