Are there things we could have learned from them that are lost to time? Well, yeah, and that itself is bad, but preservation is simply not feasible, same as we don't store every single piece of information nowadays, we can't store all of language for the same reason it's interesting in the first place: It's alive.
It's also worth noting, there's a whole, whole lot that is bound to be uninteresting beyond historical knowledge and that deserves no more respect than, say, food.
It also seems like the past is being romanticized out of all proportion. I’ve lived in a few countries now, and it’s funny how far off the mark people are in their perception of places I’ve spent many years living in and still visit regularly. There’s no way people can have such a faulty perception of different places in current times, but be more accurate when looking more than a generation or two into the past.
Plus, it is all the more exciting to think about what caused some languages to exist and thrive for so long, and the information about the past they retained.