I'm surprised you're clever enough to have found the button but are unable to figure out why this made it to HN's front page ...
In order to do so, you have to scroll to the bottom of the page. If you scroll to the bottom of the page, you'll notice that there's a "save settings" button, and without clicking on the bottom, you'll be unchecking them for nothing. And if you notice that button, you're going to notice "unsubscribe from all emails" link right below it.
I don't see that as being more crappy UX than the rest of the Goodreads design.
As a comparison, look at meetup.com, a similar endeavour in a lot of ways: their email notification screen[0] has a 'turn off' button before any of the individual checkboxes, which turns them all off (except password resets and the like).
If you're asking this, in the context of a discussion about UI, the answer is almost always "no".
I've seen this mentioned a lot of times on various forums. GoodReads by design doesn't look as good as any other social service we use now. But I am curious, whether that can be something an incumbent service can work on.
Providing great design and with GoodReads functionality, would that work for the new service?
Pointing out one part of a UI has bad UX doesn't imply that the author thinks the rest is better.