All of this creates a situation where only really players who own a lot of SPS and also have a big card collection can get out on top in Wild mode and earn more than what it costs them.

You're right. Prior to the current change, I earned a decent amount of SPS playing in the modern format. Now that I am forced to play in the Wild, not only is there a 90% reduction in SPS reward, but I also observe that my winning rate dropped to 10%.