Same reason we study and do research in biology and fields in general. Understanding more about biology, whether in neuroscience or elsewhere, is the fundamental backbone of medicine. Do you want to live in a world where we don't pursue scientific research into things because they seem scary to you? Does it not concern you us building AI smarter than humans, while knowing little to nothing about our own brains? Before we start fading in relevance, we ought to understand how our own bodies (and minds) work! So in fact I think the exact opposite. We should be doing much more work in understanding our own biology (as long as it's ethical).

I definitely believe that this technology will get misused. But I expect the researchers are thinking of helpful medical applications. Perhaps to aid people with locked-in syndrome?

Edit: More interestingly, it would be amazing if this could show us someone’s perception rather than what they’re looking at. That would be tremendously useful to therapists.

Cause it has huge medical implications?