Test reporting is something that seems relatively unimportant at first. If you're building an application using continuous integration then your tests are fully automated and won't ever be seen by a human being unless they fail. Ultimately your tests should come down to a simple 'pass' or 'fail' that the CI server uses to know whether or not to deply the newly merged code. So why bother with reporting? They can still be very important.
Simply, good test reports are useful for finding the cause of failures, and for proving that your tests are in-depth and working. Like tests themselves, a test report is evidence that things are correct, at least within the bounds of what tests you've implemented.