Let’s get something straight, API Developers of the World: Your JSON API should include hypermedia links. (and it might help to do it using HAL). Why? I’ll give you three reasons. This list is not exhaustive.
Reduced coupling between API and Consumer
The consumer doesn’t need to know the structure of your API URLs if they’re being handed it. In fact, they never have to build a link again if they know where in the response to find the link they’re looking for.
If you make an authenticated request, and a link is advertised in a response, (i.e., being sent on behalf of a logged-in user) that means the user can access that resource. If it doesn’t, they can’t. So, your app developer knows whether to grey out that button or not.
You want developers to use your API? You’d better make it easy to navigate and explore so they know what they’re working with. Try using the GitHub API. It’s easy, and it’s a joy. Why? Hypermedia, that’s why.
Convinced? Great, go to it.
For further reading, Mike Kelly frequently writes about hypermedia and APIs.
Heckle me on Twitter @basicallydan.