Several miners and pool operators have, at various times, requested a prioritizetransaction API, or have requested that the current one be made more accessible. Right now the flow to use it requires that you write a program which interogates mempool and finds transactions to prioritize for some use-cases.
While I think the API is sufficient, it would be nice to have a simple python wrapper which could, for example, completely emulate the old priority mechanism (then we could remove it wholesale :p).
We might also add a way to prioritize while submitting a transaction, but this wrapper could easily provide that as well as a demonstration (IIRC you can currently do it by prioritizing the hash and then submitting the transaction).