The Kingdom-space of Dominion is large enough now that the game feels robust to certain combos that would have felt game-breaking when the card pool was smaller.
Do you agree?
Has this changed your philosophy when designing/developing cards?
I wouldn't say my philosophy has changed, but rather that it's always included a "how many cards are there" factor.
A two-card combo that requires two specific cards isn't a problem once you don't see it that often. If they're in the same set you see the combo too much, if the combo is dominating (and not also "we always love doing that"). If they aren't you don't... unless you have a particular mix of expansions that you totally might. If the combo is Capital plus Mandarin, well maybe you just bought Dominion, Hinterlands, Empires. That's not some ludicrous scenario. But nevertheless, if it's a specific two cards and they're in different sets, I feel less worried. I factor that in. Like, Feodum didn't get to kill Masterpiece.
If it's a card plus a category of cards then it's a problem; a card that's broken with Militias is just broken. If it's three cards then man whatever. I did fix the Masquerade pin, which was two cards plus a category. I mean that's another thing: what am I giving up by fixing the problem? If nothing, probably I fix it, even if it's a two-card combo that won't come up much.