I will a little explain the thought.
On the one hand, the main forms of government open during the first era. It is possible to pass then to the republic and to play rather successfully till the end of the game.
In my opinion, it would be interesting to make the monarchic and republican form of government for every era, everyone - is a little more effective than previous. Various forms of the monarchy and the totalitarian forms of government in general are adapted for long war, republican forms - for development of technologies.
On the other hand, in the editor there aren't enough settings regulating efficiency of the forms of government. "Rate Cap" at a certain stage of development becomes irrelevant as we will come across restriction of "Minimum Research Time (turns)". "Worker Rate" at late stages of a game when the whole country is put in order and is covered with network of the railroads, too isn't too important.
"Standard Trade Bonus" - perhaps, the only really important parameter, but is quite difficult to do a large number of the forms of government only on his presence or absence

.
Parameters of corruption are important, however it is more or less successfully possible to play also at his rather high level.
Parameters of support of units are important in the first half of a game, then don't become basic (or money enough for the maintenance of any armies, or, due to use of the railroads and a regrouping of troops of rather small army.
With the third party if to make on the republican and monarchic form of government for every era, then how in it the game artificial intelligence will be guided?