It's part of the rigged system. Trump has illuminated that by suggesting a "no moderator" style of forum. That won't happen, but the suggestion in advance sets up post-debate argument of how the moderator was actually a partisan participant, thumb on the scale.
The candidates can decide not to participate. The commission should be abolished and direct negotiations between the candidates will decide the terms of the debates.
Listening to a local radio show recently, the hosts were miffed at the RNC for accepting these moderators. The hosts lamented that the GOP always caves into debate negotiations like this.