> why don't you want to know when it's fixed?

Knowing when it is fixed/closed is very much different than getting emails about every single comment going on about that issue.

Starring issues (as in Google Code Project Hosting) meant "I want to see this getting fixed" and subscribing issues on GitHub does not show anything like that. If I am not mistaken, you only see a list of people “participating” to an issue, you don’t get to see list of people getting emails about that issue.