Why playing as the Joker in Batman: Arkham Asylum is an awful idea

After seeing the preview of playing as the Joker in the upcoming Batman: Arkham Asylum, I can't help but be dissapointed with the entire idea. At first it is enthralling and ingenious, but upon further inspection, it's bound to be nothing but a let-down.

The Joker is an amazing character. In fact, I think he's one of the greatest roles ever created. Thanks to his total insanity, playing him means being unpredictable, constantly providing random acts of cruelty and being as disturbing as possible. On screen, portraying this level of psychotic behaviour is tricky but wonderfully rewaring when done well. 

 But in a video game, randomness is never available to players. There are prescribed moves, motions and abilities available in given situations. There is no chaos, no improv, nothing shocking whatsoever about what'll happen when you press a particular button. And that will ruin the fun of the character. By putting The Joker at our fingertips, what makes that character great disappears. 

I hope to be proven wrong. But I fear I'm right, and what originally seemed like it'd be loads of fun will be sadly dissapointing.