If a community really wants to severely punish something that's legally not a crime, jury nullification enables the community representatives to enact whatever extrajudicial punishment they want (e.g. the existing examples of lynching or "honor killings"/"honor rapes" in certain communities) and then protect these punishers from the legal system.

To a certain extent, yes, but the punishers need to be tried locally, too, for this to work.

It's in only one direction, because a jury cannot form itself and pick a victim to falsely convict.

A jury can still falsely convict, but a defendant can appeal a guilty verdict.

Non-guilty verdicts are more final.