Agreed, but... Casimir Jagiellonczyk... Surely a papist puppet.
To be honest with you The Commonwealth(the lithuanians were there too! Duh! They were sitting on our throne!), was a very fragile, and in my opinion from-the-start a doomed nation. Its size, mutli-etnicity, decentralized government, made it one of the most weakest states in those times(Big country does not mean strong country).
There are many critics of the Commonwealth on both sides(Lithuanian and Polish).
There were certainly disadvantages to a decentralized government, but centralized governments had there own problems, which should be reflected in the game. The 17th century crisis was largely a reaction against the centralizing tendencies of European states at the expense of the traditional nobility. In the case of Poland-Lithuania, would it have not faired better by favoring further decentralization and accepting the Ukraine as a partner in the commonwealth? Arguably, the decision to limit the szlachta (& not include the cossacks) resulted in its own 17th century crisis. The Republic had been very strong with healthy internal political debate before the middle of the 17th century. Compare the situation in Poland-Lithuania to the English Civil War or the Fronde in France. Is it so clear that Poland-Lithuania was doomed to failure? Decentralization in Poland-Lithuania encouraged support from a wide body of society regardless of ethnicity and religious affiliation (observe the support and preference of german burgers in Royal Prussia for the Republic as oppossed to Brandenburg.) I believe that attempts to centralize the state (not to be confused with the army) would have shortened the lifespan of the Republic.
I suggested using the centralization/decentralization slider to mimic the development of the state, but it is as much about inclusion/exclusion within the state. Geographically, power was diffused through the sejmiki in Poland, while the major cities of Royal Prussia maintained considerable power. At the same time, a wide scope of the nobility (poor and rich) and some burgers participated in the Republic's political life, at least until the mid-17th century. Can the same be said of France and England? Centralization was carried out to certain extent (Much less in France), but did government become more inclusive? Was the result completely positive?