I think the whole thing of most email subscriptions is that most people don't use email the right way. Most subscriptions are stuck in an old fashioned way of doing things, and one of them is that you have to officially sign in before you can unregister.
I think your second point is much better, because the realy problem here is that people still USE subscriptions. So don't try to convince them how to do their unsubscription, but rather spend your energy on cenverting them to RSS.
