And KingZog's comments after their game together were interesting, taken apart from this context. Specifically, the point about play style and understanding of the game influencing how you create cards.
Without a nuanced understanding of the game flow and progression, and using concepts like "numbers of shuffles," you might not be able to see why Bomb is not good. Yes, I know it's not good, but essentially it's a cheap card that trashes a card, and trashing is generally good, so alright. Except the trashing is the slowest it can possibly be. If the flow of a Dominion game were different, that might not be as bad as it actually as. But as it actually is, by the time you've used it to get rid of any noticable amount of your starting cards, any strategy has already grabbed up half the victory points. (As it's been pointed out, you have to buy the new Potion variant, then this card for each card you want to trash, taking up all your buys.)
At one point he responded something like "So it takes a few more shuffles to get things going, so what?" This is something interesting, because I often find myself thinking this way. Well, I can't think of a specific example off the top of my head, but I'm pretty sure I've lost quite a few Dominion games (against Bots and in real life) by thinking along these lines. As a beginning, or even intermediate, player, you don't quite have a feel of the pace of Dominion games. Unless everyone is adopting money strategies, newer games tend to go on for a lot longer because people buy a lot of action cards but don't really know how to build engines or balance them.
