We all love the concept of a new biome/structure to help make the deep dark feel less empty, but as of now, there's not a whole lot of incentive to exploring it.
As of now it feels a bit empty and not a whole lot of loot that gives the player reason to challenge such a difficult mob like the Warden. That is why I believe the Ancient City should be a key role of Minecraft's progression by making the Ancient City a vital part of crafting Netherite tools. As it stands, Netherite is the current best armor in game, and to obtain it, you simply just need to grind a bit in the nether for ancient debris, which is a bit underwhelming to obtain such strong items. By maybe making the crafting station only accessible through the ancient ruins, I believe it adds quite a bit of challenge and incentive for the player as it is not necessarily needed to beat the game either. It also forces the player to be much more careful around the warden, as they will only have diamond armor and it makes the entire structure much more terrifying and raises the stakes quite a bit.
The namesake is also a neat detail that would benefit from this change as you need ancient debris to make netherite, as well as a crafting station found in the ancient ruins, so it adds a bit of consistency as well. Overall, while this change is more of a way to make the game more challenging, I believe it increases the longevity of the game overall and adds a rewarding challenge to the player.