Yeah, or even if the decisions for governments/social policies was not permanent, I think each government would need a much larger focus. Like at least once you get to the T3 governments now, it's interesting that you have some exclusive policies. Like, for me, probably 80% of why I like Democracy best is the New Deal policy card, which is way better than any other policy card at the time IMHO. Like if Merchant Republic did not let you run the Serfdom card, ya, that would definitely change your thinking about which government to run.
I wouldn't mind if if they got back to the old system of "legacy" government being a permanent future bonus, rather than simply a policy card that was an opportunity cost to slot in the rest of the game. Like if Oligarchy gave you a permanent +4 combat strength for melee units, vs a permanent +1 amenity/housing like in Classical Republic, and not simply just a card to slot in later, that might change your decisions. That would give you that balance between choosing a government and having that decision stick with you the rest of the game but you would still be flexible within the government to change out policy cards (potentially with the caveat above where the choice of possible cards is different in each system).