O'Connor was a frustrating figure on the court in the same way swing voters are frustrating figures in our democracy. In some ways, it's easier to deal with an extremist than a moderate: At the very least, you always know who you're talking to. Swingers bat both ways. They're cagey. They're unpredictable. They could be holding sticks of dynamite behind their backs.
The difference between O'Connor and Joe Shmoe swinger, of course, is that O'Connor is an extremely smart and savvy legal thinker. She didn't align herself in the middle of so many legal debates because of any lack of understanding for the law. She placed herself in the middle largely because she truly believes that legislators should create our laws, while judges should merely interpret them.
Despite the posturing of the more conservative justices on the court—Scalia being the prime example—they're as activist as the liberals. It's the justices at the extremes that most want a clear shot at reshaping the legal future. (Keep in mind that justices' interpretations of the law become the law.) That's the main reason why Bush will attempt to appoint the most rabidly conservative legal mind he can find, someone Scalia can hop right into bed with. Bush will do this not because he believes justices should act with restraint—an unlikely argument that he makes over and over again—but because he wants to actively change the law to reflect his so-called conservative values.
Of course, the rhetoric of judicial restraint will play a huge role throughout the looming appointment battle. That doesn't mean the rhetoric will actually mean anything, though. Welcome to Reverso World. George Orwell, once again, would be so proud.