Hmmm...
I agree that - probably - majority rather choose something unknown than known when it comes to buy/not buy something. Probably there is just too many products around and companies strategy is usually to produce as big fireworks as possible so a customer would see only them.
Now, buying cards during beta (even if you can play with them) should be rewarded, I believe. One of the differences between pre-order and buying cards to not really released game is that if pre-orderded game will not be released you can claim your money back. If TFW would disappear tomorrow or there would be no players to play with one could do nothing. That's the main difference I see (of course I do not wish TFW this scenario!).
Rewarding has this - let's call it - psychological factor that it motivates. Seems like developers are willing to give $1000 in a tournament to encourage players to really playtest the game, why wouldn't they will to give for free something like gold or cards (in other words: not real money)?
I believe it wouldn't hurt at all. Satisfied player = playing and spreading positivity player. Satisfied player = supporting player. Supporting player = player telling friends about a game. Etc. etc.
So, for the good of players and the game itself I will keep opting for giving some rewards here and there (small or big, this is not as important as rewards at all).