First, the guidelines have been changed in the past. That's one of the issues everyone has with Apple's behavior - changing the rules. So let's not take the guidelines as the final arbiter.
Last.fm, Netflix, Pandora, Hulu and so forth are on the platform. They are not "essentially 'rental'" as you argue. They are subscription streaming services. They clearly "read or play approved content" as mentioned in the guidelines.
Content owners are _not_ ecstatic. They don't want an Apple-only marketplace. They want multiple healthy resellers.
Rules and guidelines have been changed for every marketplace in history as it finds its way around. Sometimes these changes are good; sometimes they're bad; sometimes they're neither.
Apple is trying something that I don't personally like (extending the rules to Amazon &c.), but just arguing that this is bad because Apple's changing the rules is a non-starter. Rules change. Sometimes they hurt people who were banking on a strategy that was based on the old rules. This is visible in pretty much every human endeavour. (The banks didn't like the rules that instituted the FDIC. They bitched. The rules were still changed.)
Last.fm, Netflix, Pandora, etc., are essentially rental in terms of IAP rules; you have time-limited access to particular content (with Last.fm and Pandora it's even more time-limited than with Netflix, since you have no real self-direction over the songs that are played per the web radio rules in the U.S.).
The guidelines aren't as clear as they could be, but as I said elsewhere, I'm pretty sure this isn't about access as much as downloadable content.
Last.fm, Netflix, Pandora, Hulu and so forth are on the platform. They are not "essentially 'rental'" as you argue. They are subscription streaming services. They clearly "read or play approved content" as mentioned in the guidelines.
Content owners are _not_ ecstatic. They don't want an Apple-only marketplace. They want multiple healthy resellers.