Anecdata (only because I don't have access to the data anymore). Customer satisfaction is so much higher when they get a one click unsubscribe. In fact, when the friction is so low, the customer is likely to start the subscription back. I say this as someone who worked in customer service automation. The worst customer satisfaction score with lowest rate of re-subscription is from companies that make it hell to unsub…
I mean, that's pretty tautological: unsatisfied customers who become not-customers, aren't part of your metric any more! The lower the barrier-to-exit is for your customers, the more survivorship bias there will be in any customer-satisfaction metrics you're trying to track.
When there's zero friction to quitting (incl. a high availability of alternatives to switch to), any time someone doesn't like your company, they'll just churn, and you'll never hear about it. So you'll think everything is great—despite the churn, customer numbers are growing, and all your non-churning customers love you!—even while there's this huge shadow-population of customers who resent your service for one reason or another, but who took that resentment right out the door with them, never bringing it to you to address.
(Not saying this is a bad way to do things, precisely; just that you have to be aware that it's the siutation you've put yourself in, especially when interpreting customer-success metrics.)
An interesting corollary to that effect, though, is that organizations that are effectively impossible to leave (e.g. utilities) will get a "true measure" of satisfaction, with no survivorship bias. If there's "marketing science" to be done on customer satisfaction, utilities are probably a great "spherical cow" simplified environment to study it in.