At Twilio, our REST API is fully documented but we still encourage people to use our helper libraries as much as possible.

It's not because we'd like to document the API less, but because there are related things - http connections, auth, etc - that need to be handled and it's easier to have the library do them. Further, the library serves to wrap the API in the idioms appropriate for the language. This may include data structures, but also includes things like variable names.

That way you can focus on your app in your chosen.. and only dig into the abstraction if you choose to.