Luckily WoW has never been a game where you were rewarded for spending money... or is it?
Long, long ago, you got rewarded in WoW for being good at the game. This meant intelligent people succeeded and stupid people failed. Blizzard took this away during WotLK.
Then you got rewarded for having coordination. 25 man raids got better loot, coordinated groups died less and got stuff done quicker. With the luck of the draw buff changes, Blizzard has indicated that they intend to give uncoordinated players buffs so that they get the same outcome as coordinated players. This is on top of the change to give 10 man groups the same gear as 25 man groups.
What do you get rewarded for now? It seems the only thing is time spent. Why not just give everyone a bot and one button to press and hand out rewards? Time spent means subscription time paid. This means spending money is the primary way to get ahead in WoW.