A whole cottage industry has just died.
Millions of dollars have exchanged hands trading on PR. Some PR 9 sites charging 1-2k per month for the privilege of a link. Hopefully Google has put an end to the industry that they inadvertently created.
I hope they don't replace it with any visible ranking that will bartered and whored out.

Should people who purchased links for PR seek a refund?

Is it better for the web if Google refrains showing any kind of ranking in the toolbar?

This is of course assuming that the display has gone permanently, but Google do seem to have been acting against the linking schemes much more since January so this maybe another nail being driven home.
No of course they shouldn't ask for a refund, If they fell into the idea that TBPR was important then hard luck to them. Maybe now we'll see a return to linking for the site visitors benefit. Though I doubt that will actually happen as links and anchor text will always remain important, as Google and Yahoo rate anchor text quite heavily in their respective ranking processes.