I think I get your objection now, but it doesn't apply. Jury nullification is absolutely based on the facts, and is not supposed to be arbitrary, nor is the power supposed to be leveraged lightly capriciously. It is supposed to be an act of conscience or protest.
This false distinction didn't always exist. For centuries, juries were considered to be able to decide based on the law and facts of the case. Everything was presented to the jury, thus the jury could decide on the whole of the case with all of the facts, including being able to decide whether the current case is a misapplication of the law, or the application of a bad law.
Then judges started discussing evidence exclusion in chambers, away from the jury. That was reasonable, you don't want to prejudice the jury with evidence that couldn't legally be used against the defendant. That's equivalent to jury tampering by the prosecution. Then the chamber and bench discussions grew to encompass almost everything. Now juries only see and hear exactly what the judge wants them to. The judges literally took away a power of the people and gave it to themselves for their exclusive exercise.
If the Constitution is the Supreme Law of the Land, jurors should be bound by what the Constitution actually says, rather than by anything judges say. The Constitution forbids cruel and unusual punishments. If a jury would find that the statutorially-defined sentence for a statutorially-described crime would be a grossly unreasonable punishment for the particular action actually performed by the defendant, the jury has a duty to acquit.
A major problem with the legal system in this country is that it relies in on many factual findings which are not only decided by someone other than a jury, but are often decided before the defendant is even alleged to have committed any crime. Some judge somewhere decides that in some circumstance it's not grossly unreasonable for cops to kick in a door two seconds after pressing the doorbell button, and it becomes almost impossible to challenge the reasonableness (and thus validity) of a search where a cop pushes the doorbell button, waits two seconds, and kicks in the door. Even if the doorbell had a sign saying "Bell bust--bang", pushing the non-functional button would make the search "reasonable".
I would really like to see FIJA work on educating the public about prosecutors' and judges' illegitimate tricks, and encourage jurors to be skeptical about their openness. Suggest to jurors that if prosecution and defendant both seem oddly silent about something that should be relevant, it's possible the judge illegitimately prevented the defense from presenting information which would have clearly compelled an acquittal, and such possibility may be a basis for reasonable doubt.