I don't know, but this is a good question to ask.
The problem with the old cards was that they were random, which removed strategic play from the equation. You couldn't plan for anything besides getting lucky or holding a card for a long time, which was more of hindrance the longer you held it. We didn't need to lose the old card effects, we just needed the ability to actually use them on demand. Balance was always good. Arrow and Spear were mostly good. Bole/Ewer/Spire were situational. If you got one of the latter three at the wrong time they felt useless despite having powerful effects and you couldn't do anything about it.