I would say that jury nullification isn't just some accident of the legal system, but the primary reason we have juries in the first place.
Judges will say that juries are meant to just decide the simple facts of the case. But what sane person would ever design a system that assigns 12 random untrained nobodies to do that task? If all that mattered was judging the facts of the case, why not have 12 legal scholars instead? Why isn't "juror" a profession, just like being a lawyer or judge is? If we want people to just apply the letter of the law to the facts of a case, why not fill juries with professionals, each who had a legal degree, and who have sat as jurors hundreds of times? Judging evidence and reading law is a skill. And it's one that can be educated on, trained, and practiced. Why do we have amateur juries, when professional juries would clearly do their purported job so much better? Or why not just do what some countries do, and have most or all trials decided solely by judges? What exactly is the point of a jury? Compared to everything else in the courtroom, the jurors, the ones actually deciding guilt or innocence, are a bunch of untrained amateurs. On its face, it makes no damn sense!
No, the true reason, and really the only reason, we have juries at all is so that juries can serve to judge both the accused AND the law. Juries are meant to be the final line of defense against unjust laws and prosecution. It is possible for a law itself to be criminal or corrupt. Legislative systems can easily be taken over by a tiny wealthy or powerful minority of the population, and they can end up passing laws criminalizing behaviors that the vast majority of the population don't even consider to be crimes.
The entire purpose of having a jury is that it places the final power of guilt and innocence directly in the hands of the people. Juries are meant as a final line of defense against corrupt laws passed by a minority against the wishes of the greater majority. An unaccountable elite can pass whatever ridiculous self-serving laws they want. But if the common people simply refuse to uphold those laws in the jury box, those laws are meaningless.
THAT is the purpose of a jury. It is the only reason juries are worth the trouble. A bunch of rank amateurs will never be able to judge the facts of a case better than actual trained legal scholars with years of experience. But by empowering juries, it places the final authority of the law firmly in the hands of the people. That is the value of having a jury at all.
Jury nullification is not just some strange quirk or odd loophole in our justice system. It's the entire reason we have juries in the first place.