A couple of days ago, an interesting thing happened. Our Department secretary emailed me, in my capacity as Graduate Director, to find out if student A was eligible for an MA degree. When I got to checking, I confused student A with student B, and checked that student B is eligible. Then I emailed our secretary and said that it was all fine. Consequently, I assume, she formed a justified belief that student A was eligible for an MA degree. But this justified true belief wasn't knowledge, since it relied on my testimony, and I did not know whether A was eligible for an MA.
Shortly thereafter, I realized my mistake. I then checked whether A was eligible, and found that indeed A was eligible. Next, I wondered what to do. Our secretary did not know that A was eligible. But she did, as a result of my mistake, have a justified and, as it happened, true belief. I could easily turn her justified true belief into knowledge by emailing her about what happened.
If knowledge has a value over and beyond the value of justification and truth, then I had a reason to email her. But it seems like it would be pointless to send a correction email under the circumstance (or at least, giving her knowledge would not be a point). And, if it would be pointless, then it seems that there is no value over and beyond the value of justification and truth.
However, a colleague suggests that perhaps the right interpretation of the situation isn't that there is no value in knowledge over and beyond justification and truth, but that there is so little value that it is outweighed by the disvalue of bothering a very busy person with yet another email.