Here's my personal algorithm for handling commercial email that appears in my inbox:
1. If I'm highly confident it's spam, mark it as spam. (Very rare necessity singe gmail catches spam pretty well).
2. Otherwise it's something I have subscribed for, perhaps without noticing (opt-in by default from some service I have used). Look for the Unsubscribe link, click it.
2.1. If the Unsubscribe link IMMEDIATELY unsubscribes me (landing in a page that just confirms I'm already unsubscribed), ok, then just delete the email.
2.2. But if ANY additional interaction is required--choosing a reason for unsubscription, having to click another button--after finishing this, I will also punish the sender by going back to gmail and mark the email as spam.
I sympathize with your position, but the problem is that you're forcing them to break the HTTP semantics (since a GET request - clicking a link - should be a safe action[1], without side effects like unsubscribing people), which then prevents anyone else from relying on those behaviors. This is why products like Web Accelerators died, and current prefetching features in browsers must only load URLs that are specifically marked as safe.
Personally, I think if you voluntarily subscribed, it's not too much of an effort to click a button after the link to confirm the subscription. If you didn't, then you should mark them as spam regardless of their unsubscription link.
"login to unsubscribe" is worse, especially for cases where I'm not sure off the top of my head what my login details were. I just want to decrease my mental overhead and now it increased by making me think of that.
Why is the mailer asking you why you're unsubscribing a punishable offense? Mailchimp does this by default on any of their unsubscribe pages (which come after you've been unsubscribed).
If a service puts me on a subscription list without asking me, and then at the unsubscription page throws a questionnaire at me as to why I am unsubscribing, I take that as dishonest behavior.
Obviously I am unsubscribing because I never subscribed in the first place!
Depending on how completely unrelated the subscription is to whatever I signed up for (say I signed up for online image hosting, and they start sending me emails about their fantastic paid backup service) then I mark it as spam even if the unsubscribe button is easy and single-click.
And for companies like MailChimp, it's a way to identify customers who are spamming people, and (hopefully) closing their accounts. If a high percentage of users are responding to the feedback form with "I never subscribed" then it's worthy of investigation.
1. If I'm highly confident it's spam, mark it as spam. (Very rare necessity singe gmail catches spam pretty well).
2. Otherwise it's something I have subscribed for, perhaps without noticing (opt-in by default from some service I have used). Look for the Unsubscribe link, click it.
2.1. If the Unsubscribe link IMMEDIATELY unsubscribes me (landing in a page that just confirms I'm already unsubscribed), ok, then just delete the email.
2.2. But if ANY additional interaction is required--choosing a reason for unsubscription, having to click another button--after finishing this, I will also punish the sender by going back to gmail and mark the email as spam.