There are layers of reasons as to why this is a horrible, terrible, no good, bad idea.

• Making Reward cards cheaper than Rebellion cards.
• The market for Reward cards is limited, flooding the market with more cards is a terrible idea and will only hurt the game.
• CL is scheduled to rotate out in ~4 months, at which point the Reward cards will only be playable in Wild.

50 DEC to 'unlock' a RF, Common card- at current prices is.... 3 cents. At those prices, there will be plenty of cards unlocked and available on the rental market. You drop that price down to $0.015 and you'll end up with:

• Less DEC burned, less chance of engaging "The Wheel"
• More cards unlocked, undercutting the current market
• A clogged and oversaturated market for Reward cards- causing many to lose $$ on unlocking their cards.

And remember- this is all only relevant until CL rotates out of Modern. Once that happens, well, much of the relevance of these cards will be lost.