Most people leave honest feedback, and there isn't much of a knee-jerk reaction if you did your job as a seller. Holding your feedback 'for ransom' isn't cool, and it isn't good business.
I can't understand why you'd support this type of a system unless you're one of those rip-off artists holding people's feedback for ransom and then leaving them negative feedback after you shipped them a 50Meg ripped MPEG of LotR when the item description was "NIB Lord of the Rings Trology DVD Collector's Set"
Go insult people who aren't 50 times smarter than you, or at least post something half-way intelligent, instead of pointing out to the entire world how stupid you are. If your parents read that post, it would probably make them cry.