History, paleontology, anthropology, cosmology, and other fields have highly educated people spending their entire lives dedicated to recovering the past when it couldn't be preserved or when people tried to purposefully destroy it.
Knowing about the past adds to our understanding of the universe and guides us into the future. There is no downside for our current culture to know about the past.
Sure, everything is ephemeral, but these works have impacts on people's lives and ambitions. How many folks are named after movie or TV characters? How many people got into software after watching The Social Network?
I follow a couple of small communities of amateur VHS archivists. Through this I randomly watched the marketing material of an 80s/90s era MLM, which finally put into context a similar MLM that my mom had fallen for when our family was at a financial low point. This random bit of preservation helped me to better understand a part of my family and upbringing; far better than I could reading a Wikipedia article about the company in question.
