The bread and butter for RPGs is questing, and the Radiant AI allows the player to be creative in how a quest is completed in Oblivion. For example, if you have to steal a rare gem from a shop owner you could walk right in, whack him over the head, and take it. You could wait until he leaves, and steal it. Or if you find out that he keeps it with him at all times, you could follow him to a secluded spot and then pants him, out of the sight of guards. It comes back to freedom and immersion. In the words of Todd Howard, lead designer on Oblivion, it's all about options.