My mistake. It's a pretty easy fix, non-impactful. I'm working on it now and should have it in a pullreq for forrest soon.

The reason you would want something like this is because normally, p2pool pays out to the same address over and over when it constructs its coinbases. But this isn't ideal: if you are ever identified, then your entire mining history might be laid bare for the world to see. You must maintain perfect opsec, forever, if you desire stronger financial privacy under this method of mining.

If you rotate keys on a programmable basis, then you get payouts to *different* addresses with no additional effort on your behalf and it is somewhat more difficult to correlate which addresses are grouped with one another until you spend them and group them yourself.

You could have achieved an approximation of this by having miners who were inputting some different addresses and accepting miner-supplied payout addresses, but then you have to do it by hand and it was really annoying.

In my opinion, p2pool users now have arguably more privacy even then solo miners, by using this option, at the expense of a larger coinbase.

(fwiw, considering the spam nonsense going into the blockchain right now, I hardly think miners demanding additional privacy is at the top of the list of UTXO bloat.)