Not really happy with this solution either though. The more I consider the Free Buildings issue the more I feel it should not be an automatic thing. The Settlers earning promos to achieve these would be a suitable solution (though I'll have to be careful not to overload the AI eval on promos!) but even giving positive buildings for free can have a negative effect on gameplay.
IMO, any use of the Free Buildings tag there should be applied into a modmod as I don't think players will be able to agree on what should and shouldn't be free. I COULD, however, add an option that can turn the whole tag on or off.
EDIT: @HYDRO: My arguments against any free buildings at all are
perhaps best worded here. Rwn proposed some interesting countersolutions but I still think we would have a player personality polarization issue with this modification being a default either way.