Some of the cards are on rare mobs and should drop rarely.
I, too, have wrestled with giving out more or less information. The last few patch notes I have written have had things like "...x will now happen rarely..." I expect I'll be asked to clarify in a thread when that stuff goes live.
I'm fine with the "damned if you do, damned if you don't" thing in this case. Like I've said before, as a player I always wanted to hear from devs and talk to devs more - it makes me want to stay with the game. Now that I am one, as long as my bosses will let me talk, I'm going to do so.
That all said, I'll check again to make sure I got the right number and they are dropping. QA tested these and gave me a green light, though, and they haven't been wrong when they've responded to a testing request.