Subscription is the process of signing up to something to receive updates, episodes, etc. So changing "e-mail me" to "Subscribe me" here would be making it a bit more abstract without really changing the meaning. And I think "I'm invited to subscribe to a bug I'm already subscribed to" is pretty good evidence that switching to "subscribe" terminology wouldn't make this problem any better.
I agree that the checkbox should be checked if you receive e-mail about the bug for any reason that Launchpad knows about. (This will gradually become any reason at all, as things like project subscriptions replace things like the launchpad-bugs@ mailing list.) And the checkbox should also be disabled if Launchpad is currently unable to unsubscribe you individually. (Which should gradually become never.)
Subscription is the process of signing up to something to receive updates, episodes, etc. So changing "e-mail me" to "Subscribe me" here would be making it a bit more abstract without really changing the meaning. And I think "I'm invited to subscribe to a bug I'm already subscribed to" is pretty good evidence that switching to "subscribe" terminology wouldn't make this problem any better.
I agree that the checkbox should be checked if you receive e-mail about the bug for any reason that Launchpad knows about. (This will gradually become any reason at all, as things like project subscriptions replace things like the launchpad-bugs@ mailing list.) And the checkbox should also be disabled if Launchpad is currently unable to unsubscribe you individually. (Which should gradually become never.)