Thanks for playing, and for the detailed feedback!
You're right about the card essentially being lazy multipliers, as during play tests we found players wanting any additional cards (got told that 30 different cards would be ideal).
To make "good" cards (the ones that have better numbers) feel more valuable, we made them more rare, but this results in most runs having your deck stuffed with worse cards.
If we get around to improving the game, we'll be sure to tweak these numbers!