The rule has been in the T&C since launch of the AppStore. Apple didn't provide a mechanism for in app purchase of subscriptions, and so was lax in enforcing it. But it isn't like this is news to anyone who read the T&C.
I saw a similar comment in the other thread about this. Regardless of whether or not it was noted earlier, it is behavior that many people consider unacceptable. Many App developers are being forced to change their practices, and find the new rules too burdensome to continue.
Which is the best solution to this problem. Please let this be the first use of the remote kill functionality. I have an iPad. While I would be a little sad to see big players like Netflix and Amazon pull their apps, I will be delighted with the uproar when the general public finds out about this. Unless the companies cave to Apple, this will make the Objective-C debacle look like small change.