Curiosity did not have a camera on the sky crane that was able to image the lowering of the rover. I'm happy that Perseverance does have cameras, resulting in this awesome video.
What was the motivation to add those cameras to Perseverance? Were they needed for the landing manoeuvres (I doubt it, as they were covered until the rover was lowered)? Did they allow to learn new things about the sky crane operations that were not yet learned from Curiosity's successful landing? Or was it just a PR gimmick that was evaluated at lots of good PR for little cost?