Slide to Unlock

What is the point of the ‘slide to unlock’ screen on the iPad?

The iPad sits on the table when not in use. The power button isn't going to get pressed by accident. (I have never used an iPad — I am just guessing.)

Simplification: Just press the power button to turn the display off and press again to turn it back on.

Pass code locking complicates this matter. I say that it should be asked for straight after pressing the power button. In other words, just remove the slide to unlock stage.

On the iPhone or iPod touch, I think the pass code lock makes slide to unlock redundant. If slide to unlock is turned off (something that should generally not be done) then slide to unlock does serve a purpose since the button might be pressed by accident in a pocket. (Although I have no experimental evidence to prove or disprove this hypothesis.)

Using the iPad as a photo frame

The iPad's photo frame mode is activated by pressing a button on the lock screen. Where would it go if the lock screen was no more?
It would be an app, like everything else.