It has no value for users, but it would be really helpful to write tests. Currently we tend to write some unit tests as integration tests. See e.g. https://github.com/playframework/Play20/blob/master/framework/test/integrationtest/test/ApplicationSpec.scala#L212-L257

The `FakeRequest` type has been introduced only in the `play-test` module, but it if we had defined a smart constructor in Play directly we could use both it in our unit tests, in Play core, and in user tests (instead of `FakeRequest`).