Interface Quirks – Why do we need to confirm a action after I clicked the original?

Trying to unsubscribe from a email, clicking in the unsubscribe button opens a browser window where you need to enter your email and click Yes, unsubscribe me even after you clicked the original button. Do they think we changed our mind in the 2 seconds it takes to open the window. I would prefer the option to resubscribe, rather than wasting my time or trying to deter the action.

design