The vote is the payment. That's why I grow my HP, it's an investment. The votes a witness receives for their “free” applications are forms of payment. Of course if it stops working a few hours nothing happens, but if it's months or definitive, the votes that supported it should be withdrawn, because that's what they were given for.
Should we continue to support a witness for what it did in the past, if in the present it is not doing anything? The best thing about Hive is that there is no election every 4 years and we can vote at any time.
That's all reasonable with this additional set of guidelines for it clarified.