It's a national sport in South Korea (IIRC). At least it used to be in the BW days. Companies used to pay players for their StarCraft team... they take it pretty serious there. If I'm playing a game, say "GL HF" and get an oriental response, well at least I know there's nothing I can do haha.
This was only done to stem cheating. In the days of Diablo 2, I can't tell you how many Stones of the Jordan I hacked. Some people even sold these hacked items on Ebay for real money. The online requirement is to stop that.
*You much connect once every 30 days to verify subscription
The new Co-op and Archon modes are quite fun as well. I've become much more of the casual SC gamer myself... certainly the online PvP stuff has gotten far too intense for my family schedule