My guess is that the writers of the top pages, who will now make less money off those pages, are (considering) suing for the future revenue they would have made under the old payment structure.
They're probably particularly pissed now that those pages have aged in Google, and proven their value (writer took the risk).
Jason mentions how the old payment structure led to a "happy few and frustrated many." I have a hard time believing there's enough revenue from the contributions of the few to significantly improve the compensation for the many.
You would think they would have just suspended any new revenue share pages. So they go people writing for them under the pretense of residual income, got the content and had it updated for them then removed any benefit for the content producer.
One things for sure, the already bad quality of mahalo will get even worse when these writers who were motivated to maintain quality articles by residual income are gone.
They're probably particularly pissed now that those pages have aged in Google, and proven their value (writer took the risk).
Just a guess, IANAL, etc.