Because we want to learn from our mistakes. Whether it came from a wild animal, a lab, or something else there are lessons we should learn to help prevent it from happening again.
It's an overused example, but it's a good one. Flying is extremely safe. Not because it's an inherently safe activity, but because every time something happens we stop and ask why. We don't accept simple answers like "the pilot screwed up" we try to find all of the root causes and contributing factors. Then for each of those we try to find a mitigation to avoid the problem in the future.
It's not unreasonable to want to know what caused this pandemic so we can try to avoid the next one.
It's an overused example, but it's a good one. Flying is extremely safe. Not because it's an inherently safe activity, but because every time something happens we stop and ask why. We don't accept simple answers like "the pilot screwed up" we try to find all of the root causes and contributing factors. Then for each of those we try to find a mitigation to avoid the problem in the future.
It's not unreasonable to want to know what caused this pandemic so we can try to avoid the next one.