Why rework art that "works"? That's not the right approach; instead of destroying the power of a unique artifact, they should focus on making non-performing items more substantial. It's all about countering strength with strength. RiMpel2 expressed it more accurately.
People stopped caring about the aesthetics of uniqueness a long time ago. Now, they focus on the specifics – how certain actions affect the balance and gameplay.
The Amulet of Chu, among other things, limits the player's development options. For example, when playing with the Amulet of Chu, everyone only chose Water and Fire – for transportation. Earth, despite its usefulness, was rarely chosen, simply because the Amulet of Chu was almost guaranteed to be present in the final stages.
When the Amulet of Chu was banned, suddenly three elements became useful, and people even started experimenting with Air from time to time. They also started taking various magical skills more often, including Intelligence, which were considered useless with the Amulet of Chu. They started taking Wisdom and building towers more often. Artifacts like the Black Orb and elemental spheres became useful. Players became more careful when moving around the opponent's territory, conserving mana, and, conversely, the practice of attacking opponents with low mana appeared. Mages finally started being used more often.
In short, the range of methods used has noticeably expanded. This has definitely benefited the gameplay.