Look, this is Robin's site and he can do what he wants. If the sale is BECAUSE of the pinside listing, then I don't mind paying the fee. But, I multiple list when selling a game (ie: MrPinball, CL, here, RGP, etc).
But, should this site be subsidized JUST by those selling games? What about all those people designing/selling mods, add-ons, etc and basically exclusively marketing here, are they being asked to pay something?
Lastly, the way it was before was a good way of doing it. When your ad was marked sold, there was a suggestion to make a donation if Pinside helped you sell your game. But, I'm involved in this hobby in another way where we facilitate the sale of many, many games yet don't collect any commission. Not only that, at the Midwest Gaming Classic we will give you benefits for bringing your games whether they are there for sale or not.
While I'm not opposed in principal to what Pinside is doing on this front, it does seem there are issues in how this change was presented and rolled out. Should you donate to Pinside if you use it regularly? Definitely. Do I think you should you be forced to do so? No. There are other sites who do that and I don't think the result is positive.
My 2 cents.
Jaz