Pensieves appear to function equivalently to a video lifelog - they give you an accurate view of things that have happened to you, and allow you to share it with others. As a teaching tool, it is a VCR. It would be very useful for DADA, if you can talk some aurors into sharing memories of real fights, but I'd not expect exposure to that prior to NEWT level classes, and having that record be restricted to auror trainees would be easily justifiable.

As an investigative and intellectual tool, it is highly valuable, of course. But for basic education? Nah.