The problem with power creep is that it devalues older cards and some players sell older cards to participate in new card sales. This is what happened when the CHAOS set first came out. People were able to sell the high value of their older cards to buy the new cards. Now though, they will probably have to bring in fresh money from somewhere if they want to partipate in sales as the prices of old cards have fallen by so much.
Power creep also hurts the card rental market for old cards which means old players can't use revenue from that to participate in new card sales as much as before.