Twitter: Don't build core-feature Twitter clients, we probably won't approve them. Atta: I built a core-feature Twitter client! Twitter: Sorry, we're not approving your core-feature Twitter client. Who is surprised? How is this news? Were you expecting them to not apply their own rules? It seems like a clear-cut case, and concluding "don't build anything for Twitter" is just throwing a temper tantrum.
It's interesting to me that a prevailing view seems to suggest that developers have a right to plumb a given service for data. This worldview seems to come up most in relation to free services, so maybe it's a belief that freely consumable services via the Web or mobile give should mean a freedom to consume the same data via an API.
I feel as a user as though I should be allowed to automate my use of Internet services. I should be able to use improved clients for any service as and when I like, to get improved user experience, and to integrate them with other services.
I can imagine a law that allows this. Entirely to encourage innovation and competition.
Remember - it's the early days of the web. It took about a century after the printing press before the consequent law changes (such as invention of copyright) settled down.
I expect it to take a century on the Internet as well. Everyone should plan for the future assuming our laws from previous centuries will be found by society to be unsuitable, and will change.