As you mention, those are the symptoms you have right before your head explodes.
Would make a great disaster flick, but not a pleasant way to go in real life.

If this keeps happening with regularity, it will likely appear in a movie somehwere, perhaps like the unexplained death of drummers in Spinal Tap

Back to planes, why did it depressurize? Was it a system error, or some other reason?

Good question! It does seem to be happening with increasing frequency. And yet, as you point out, there is no serious coverage of this in the MSM.