Putting Wheel on a creature means that you can potentially repeat the effect, if you can find ways to bring the Magus back
Granted, the difference is minor, and we do expect them to swap positions soon
The Amethyst-Ruby deck is an interesting combination of control and aggro
Magic is a competitive game at heart, but understandably a lot of players just dont have a desire to play cutthroat 1v1 matches against opponents who may be taking things much more seriously, or have a huge edge in experience
However, with this, they cannot hide their beef or Eldrazi Titans behind a smaller sacrifice, their biggest power gets sacrificed
Considering the sheer number of fantastic new Commanders and constructed staples in the set, this isnt at all surprising