Everyone with a brain agrees, but unfortunately, there are a lot of people who will see "ooh shiny new leader" and give Firaxis their money no matter how janky the actual game is. There's no clear economic incentive for Firaxis to bother with free polish, gameplay improvements and bugfixes.Civ6 is just a bloated mess at this point. I would trade in all of the new leaders for one final, comprehensive gameplay polish patch.
However, if they take a look at their close competitor Paradox Studios, they might learn that the developers of Stellaris are seeing great success and immense goodwill and loyalty from their players after they created a dedicated bugfix/polish/AI/general improvement team that pushes out free updates despite the game being like 7 years old now. That game used to be even more janky than Civ VI and they managed to fix it and win all the fans back.