Following up late to this, but, broadly speaking: we mostly just haven't added these features because users haven't asked for them and we haven't otherwise gotten around to it. That's basically it. They would all be useful and/or welcome (assuming we were happy with the implementation.)

(We also don't want to necessarily just straight-up copy raw implementations, but improve on them where we can. But most of the asks here are pretty straightforward, I admit.)

> path filtering (`git log -- <PATH>`)

This already works today with `jj log`.