Does seem like you can be switching policies an awful lot in a game to micromanage.
I think a system that would work great would be where each card has 2 bonuses, but the catch is that the second bonus only comes into play once you've had the card active for, say, 10 turns. Then you might have the decision - sure, you may need another builder yet, but if you swap it out, you lose the extra bonus for it when you do want it soon.
Either that, or what they should really do is make each card "one-time use", or have limited recycling of cards. Once you swap it in, if you swap it out, you lose being able to use it again for the rest of the game.
I think a system that would work great would be where each card has 2 bonuses, but the catch is that the second bonus only comes into play once you've had the card active for, say, 10 turns. Then you might have the decision - sure, you may need another builder yet, but if you swap it out, you lose the extra bonus for it when you do want it soon.
Either that, or what they should really do is make each card "one-time use", or have limited recycling of cards. Once you swap it in, if you swap it out, you lose being able to use it again for the rest of the game.