While some of us got addicted to churning CCs to pocket and use signup bonuses, Airlines got increasing revenue from selling miles to the banks. Remember, every time one gets the bonus in terms of miles in his/her FF account, the Airline or Hotel management company got revenue from selling miles. The banks are getting smarter and soon the Airlines will be on the loosing side.
My point is that banks are partially responsible for ruining FF programs by buying vast amounts of miles from Airlines. Of course, one could only wish that Airlines would go back to rewarding flying customers once the revenue from selling miles to the banks dries up.