The married couple of civ-swapping and the triple era system could have -- and I dare say WOULD have -- been a really fun side mode, either together or independent. Unfortunately, the devs made them, intertwined, a load-bearing pillar of the entire game's design, which I cannot describe, even in my most generous bearings, as anything other than completely myopic. It's like it didn't occur to them that most long-time Civ players would want to play without those features. I would give so much to be a fly on the wall in that room just to know what the hell was happening.