Answer:
Anne's diary is so important because, while we might have still known about everything that happened back then, how else would we experience what it must have felt like to be in those situations ourselves? We still would have been in the dark and we would have so many more questions than we already do have.
Step-by-step explanation:
I don't really think this question requires an explanation since it's really just asking for my opinion. I hope this helps though :)