Okay, well, let's pretend you’re a “big time” domainer, and you do have occasion to use Moniker's auction service. Let’s pretend you own a million dollar domain. All things considered, would you feel good about signing the Moniker contract? Would you even consider it? If so, Moniker thanks you...and will reward you by soon raising their take to 20% for your next domain at auction.
Speaking only for myself, I certainly wouldn't sign anything like that or give up anything to list it in any auction, especially Moniker's. In fact, they'd have to offer incentives in my favor just for me to list it with them. Would that mean a different (undisclosed) contract? Sure would if they wanted to list my million dollar domain. Think about it.
Then think about this: Why should it be any different for other domains? If you sign their contract that is there to supposedly "protect our interests as well as yours"...if your domain sells at auction, Moniker gets their share and you get yours...fair enough, since you agreed to it. But if your domain doesn't sell, what do you get? In return for an unsold domain, you don't even get financial control of your domain back...because your domain didn't sell in their auction, they get exclusive selling rights to it for a minimum of two months and limited financial rights to it for two years. Tell me how that's for my protection and not about money for Moniker.