If a buyer doesn't pay for an item, the seller reports them and ebay can remove them - so the claim that sellers won't be able to weed out bad buyers is false. If sellers aren't able to leave feedback against buyers, we will actually see weeding out of bad sellers, because buyers are too afraid that they will get retaliatory negative feedback in return.

I think it would've been better to make the seller give feedback first, since once the Buyer has paid, the buyer has done their part of the deal.
I asked ebay if they could make a rule for when a feedback standoff occurs, that the seller gives it first, since the buyer earnt it first. They responded to say that people don't have to leave feedback, so they weren't going to have anything in their help guide about it.

If they do change the feedback system to prevent sellers from giving feedback (forcing them to report legitimate issues instead), I'd certainly start leaving feedback to the sellers who deserve it, both good and bad.