RE free cities:
I get why you can't raze them when they ask to join you. It is annoying though. Maybe they could add an option for you to resettle them- remove city, add some fraction of the pop to your nearby cities, but perhaps at some cost to you like ~gold. Maybe firaxis wants you to have a flexible military able to handle it quickly, though.
Their aggression is obnoxious. i don't know why they made them feral. Because as it stands, you
want to put them down so they stop spawning. When you bring civs back via liberation, you can see how their tech pace stopped improving. I think they should use that kind of data with free cities so they don't bounce around so much in unit tech. And set the militia to be defensive (maybe only attack units in/adjacent to their borders.)
RE polders:
I think everyone but the devs who were in the let's play wants to loosen polder placement. They said in that video that they didn't reroll for that start. Boy are they lucky- any other start and they would have been feeling pretty sheepish in the video about not being able to show off polders.
RE: other stuff
They need to rework government legacy bonuses in one of two ways: either outright prohibit stacking the legacy card with the effect while you're in that government, or making the legacy bonuses distinct from the government bonuses. This makes warmongers OP with +8 combat strength from oligarchy, and up to +12 once you hit fascism. 48 strength legions, guys. In the Classical era. Who thinks this is okay?
It also makes democracy blisteringly overpower the other governments in terms of production. I have written about it a few times, but if you actually
do the math on it, it is so much better than communism that it's just a joke. I like the power level late game, but they probably need to swap the legacies for Comm and Democracy, as well as rebalance the card distributions for the governments in general to recognize that there are new demands on wildcard slots (legacy, dark age policies) that massively tip the scales towards those governments with multiple of them. (Merch Rep, Democracy). Mostly just paring a military card off of monarchy & fascism, into a wildcard, and thinking long and hard about whether communism needs 3 military slots itself.