If you're familiar with the "list unsubscribe" functionality, support for which is implemented in Apple's iOS Mail Client, as well as Gmail and Outlook.com, you might wonder why these implementations might not allow you to land at a preferences page when clicking on the link. Clients have certainly asked me why they aren't allowed to add a step in the middle of this process -- instead of just logging the unsubscribe request, can't they ask the subscriber if they might want to receive fewer emails (opt-down instead of opt-out) or otherwise adjust their preferences, instead of losing them?
The problem here, is differing expectations between marketers and internet service providers (ISPs).
Microsoft's Terry Zink explains specifically why Outlook.com does not support the HTTP method of list-unsubscribe (which would potentially allow driving to a preferences page instead of just capturing an opt-out): Because it's their user interface, and it's up to them (Microsoft) to ensure that their users have the best experience possible, and they really intend this to be a simple "unsubscribe" and nothing more. He explains that #1 the experience is really supposed to be "you are unsubscribed," not click this checkbox or hit this button, and #2, he explains their concerns over the potential for a third-party interface not necessarily spinning up properly, resulting in a poor subscriber experience, and an unlogged unsubscribe request.
Jump on over to Terry Zink's blog post where you can read it in his own words. That, in a nutshell, is why it works the way it does, at least as far as Microsoft's Outlook.com platform is concerned.