Why an attacker should do a clickjacking attack where he could just simulate automatically the click?

Why an attacker should do a clickjacking attack where he could just simulate automatically the click?

What's the reason why an attacker should choose to perform a clickjacking attack? If he creates a malicious website, he could just perform the action automatically, he doesn't need to "trick" the user to click on the hidden iframe (so clickjacking).

So why?