Tim Bray is right, as usual.
If blogs, vlogs, mlogs, in other words, subscription systems are to grow faster, subscribing should be a one-click operation. On the other hand, the web is full of one-click nasties and if the XML icon is to be used for that operation, it should be safe. It seems to me, getting people to learn and trust the operation because they are fairly certain they can is the challenge.
Otherwise, yes: drive learning through the common interface convention. That is what hypertext has done best for decades.