SoundCloud recently made changes to the signup process for their API and is now requiring approval before any third party developer can get an API key and access the API. While I encourage API providers to be as open and transparent as possible with their API portal, documentation, and other resources, I honestly can't criticize API providers for locking down APIs and requiring approval—especially when third party developers can be so badly behaved.
Modern API management solutions allow for API providers to decide how open they want to be with their APIs, and while there are many benefits to having an open presence for an API portal, documentation, and other resources, I predict that many API providers will require approval before you get full access to resources in the future—especially if it impacts the end user experience in a negative way like it was on SoundCloud.
I support SoundCloud's decision because they kept their overall operations public and because they shared the decision so transparently on their blog. This type of transparent, communicative approach is important to helping set the tone for the API community and prevent any backlash from developers. There really is no reason API providers have to be 100% open with the data, content, and algorithms to which they are providing access, and I think that SoundCloud's approach provides a basic model that other providers can consider when they are thinking about exactly how "open" they want to be.