Generally I disagree. I won't get into details because I'm no expert on Civ6, but even a look back on Civ4 could show some difference. Personally, when I wish the AI to be improved, it is mostly not because I wan't the AI to win more often - It is because I want them to play a more interesting game. To have a more consistent strategy during a game, to take more realistic decisions, to have some human-like or historically accurate ambitions and tendencies. A major problem is the diplomatic system, which blocks any possibility for practical statesmenship and downgrades it to a childish game of good manners and meaningless decisions.