Yes, there are more mechanisms in Civ VI than in any previous games, even the base Game contained a lot of mechanisms from previous iterations that got them not untill some Expansions. But as one who enjoys Mechanisms over diversity in Civs/Leaders, I find Civ VI's Mechanisms very simple for my taste. I know it's not a Paradox/Grand Strategy game, but I want to see some deepness in the Mechanisms. Nearly everything feels abstract and shallow when played the Game for a while, especially because there is no interconnection between the mechanisms. Remove all the Civs from Civ VI, and just make copies of one Civ, and the Game will have little replayability to offer, because every Game would feel the same. The diversity in Civs/Leaders and their Unique Traits is what's keeping the replayability of the Game IMO.
AI was always an Issue in every Civ Game, and it's not like that the AI was great in those games or something (apart from DLL Mods such as VP). And Bugs and Balance Issues, you can find them in every Game, so I don't have a problem with that.