This would be a cosmetic change, but an important one. As seen on the attached Test Result Trend diagram, when the number of successful test cases rises, the diagram actually communicates the decreasing number of test failures.

This causes a subconscious impression of things deteriorating, instead of improving, so the diagram - when interpreted without additional context - communicates the opposite of the actual facts.

This applies mostly to pointy haired bosses, but to some amount to every human being, even the developers who know what the visualized data actually means.

The diagram should be mirrored vertically, with successful tests at the bottom, skipped in the middle and failing at the top. This way, when results improve, we'd see an upwards trend on the diagram.