In what? In being able to study the thousands of dramatically different ways humans can communicate. Preserving languages is about preserving data for linguist

In what? In being able to study the thousands of dramatically different ways humans can communicate. Preserving languages is about preserving data for linguistics (and other fields). We preserve a lot of things with no "real value". We preserve fossils, species (any species with fewer than 100 remaining specimens isn't contributing to any ecosystem), books (even ones that are outdated and no one is ever likely to read), websites... I could go on all day. We preserve this stuff because we can learn by studying it. Languages don't just have different nuances, they have completely different ways of putting human thought into words. They have grammars so different that a word for word translation would be no more readable than an untranslated text. They have such a huge variety of sounds that encoding them into IPA stretches the limits of Unicode's variants of the Latin alphabet, relying on many diacritic marks on top of regular characters. It's not about preserving something that gives some greater ability to communicate. It's about preserving a database of linguistic evolution and the bounds of how human thought can be encoded orally.