If the cards are used as pure randomizers, I would not want dice.
If the cards were used in card type ways, like holding a hand and determining when to use it, or building a deck for your character that gives bonuses to only certain types of actions, then I could see usages even if randomizers.
But even better are cards that do other things. Sure, those might be able to be put on a chart and determined with randomizers, but cards quicken that at the least, and enhance it when used in card-type ways.
Here's a completely made up example:
Picture making a deck for your PC, and you'll be able to have three in your hand to play when you think are appropriate. Cards have two parts - a narrative control and a bonus to a related sort of activity - you can use it for either (but not both), and you don't refill your hand until you've used all of your cards. You are playing a well connected rogue type.
A Friendly Face
When meeting with sentients who are not Hostile where at least one member is new, you may unexpectedly know one and they have a step more positive Reaction than the rest. Give a quick thumbnail of how you know each other.
MODS: -2 Target on any non Aggressive social move; -1 Success on any Stealth or Hidden move
I Know A Guy / Name Dropping
Know the closest reasonable location to find a legal or criminal service. Starting Reaction of Hostile or worse is bumped up to Suspicious and may be adjusted from there by other cards.
MODS: -2 Target numbers on social moves for the rest of the scene until a social Failure, at which point Reaction will worsen by two steps.