Back in my e-commerce days, we used to use this "one weird trick" to help reduce spam complaint rates: We put a prominent "click here to unsubscribe" link at the top of the email message. No need to scroll down to the footer to unsubscribe. What happened? Spam complaints went down, unsubscribes went up a little, then down over time.
In this context, that was a very good thing. These were emails sent to people who signed up via a double opt-in (confirmed opt-in) process, a free trial software download registration. A lot of them just wanted the free product and were quick to complain about the mail they received as a result. Even though it was double opt-in, even though it was clearly spelled out at the point of capture.
Of course, an easy unsubscribe is NOT a substitute for permission. You can't just buy some list and start mailing it and say "but it's easy for people to unsubscribe." That's the kind of thing that'll get you blacklisted by Spamhaus or get your ESP account terminated for violating ISP and ESP permission requirements.
But if you make it as easy to unsubscribe as it is to hit "report spam," you're likely to get a net positive impact to your sending reputation.