I'm pretty sure the developers got together after putting in all the content for levels one through thirty. They put their feet up on the desks, passed out the Krispy Kremes and caviar, downed a few jack and cokes, and eventually, someone said, "Hey, you think we should have an endgame?"
The head of the art department, from underneath the table where he'd been napping, awoke. "What do you mean, endgame?"
At which point Metzen said, "You know, something for people to do from levels thirty-one until the end. And like, after that."
"That sounds like... actually, that sounds like more work. Like a LOT more work," quipped Tigole. "I don't know about you guys, but I'm beat. I've been working since, like, 10:00 this morning. This job stuff is really cutting into my sex life, you know?"
An evil programmer spun around in his chair, petting a cat and stirring a martini. "I propose an alternative," he cackled. "How about we keep the game as it is, but make vague promises about an end-game. We'll release the beta with the first thirty levels and pretend we are 'stress-testing' them. In the meantime, the message boards will light up with glowing reviews. The art! The animation! The gameplay! The quests! The herbalism! (
http://www.penny-arcade.com). By the time they realize there is no end-game, they will be HOOKED! They will dream of the magebloom, just out of reach! They will fantasize about gnomes dancing suggestively in their underwear! And we shall spend the rest of the development period on the roof, tanning, while the cast of Buffy and Firefly oils our naughty bits."
Really, I think it's a conspiracy.