A couple of examples might enlighten you, Aboriginals in Australia has words in their language to describe how a kangaroo jumps, thus providing a much easier way of recognizing a single animal in a herd from others than just by separating by sex and age.
Inuit (Eskimo) have tens of words for snow, not much use to the aboriginal, but for the Innuit it is valuable in their every day lives.
The language Ubuh spoken by only Tevfik Esenc died on the same day a Danish linguist arrived in the city to document its existence. It had, as far as anybody can know any longer, 80 consonants, whereas English has only 24. !xu has only 48 consonants, the ! is used for tongue clicks.
In some languages all the history of the people is carried as tales told at large feasts, nothing is written. Great poems and histories, equaling Greek, Roman and Norse myths. Retold by generations. If those languages die, all remnants of their culture might also die.
It is also held that a multitude of languages benefit the humankind much more than a single global would ever do. Both for culture, music, art, but also commerce, peace and science. In fact, many parts of a language and a culture influences the way songs are sung, how rhythms evolve. The popularity of African rhythms in contemporary music proves that this also affects the every day lives of modern people.
Small languages need support, and revitalization, that means that all speakers of a language should have an opportunity to get software and keyboards which can support their particular language. It might be even more important in the face of corporatism where there are nothing small or marginal languages can demand.
Corporations are not benevolent towards small and marginal groups who can't earn them money. Many people can't see the benefit of using millions on preserving languages which are nearing extinction, why not use them on health care and housing?
In Iceland, a nation of nearly half a million people they have been very strict of applying old words to new ideas. Thus the national weather center is called Vedurstofa. In Norway we call it Meteorlogisk Institutt, which most people speaking a Latin language will recognize as meteorological institute. Vedurstofa means weather (an English word derived from old-Norse, which Icelandic practically is) hut or house.
That might in fact be a bit fundamentalistic at times:), most languages borrow and learn from other languages to some extent anyway. But it is beautiful.
Finally, why is each language important? Well, it is part of an human identity. It gives the practitioners of a language great pain not to be able to use the language. It saddens me that I can't take part of my grand parents Sami-language, because I never learned it in school, nor used it at home. How much I've lost due to bad communication (they speak Norwegian pretty well, but they're fluent in Sami)? And now, when they are at the autumn of their lives it is harder for them to speak at all, not to mention trying to translate to Norwegian.
The pain visited upon my mum and her generation is even grater, they were forced to speak Norwegian at school, though they didn't know anything but Sami from home. My mum has felt dum all life, because she's felt that she isn't good at writing and communicating. Last week she finished a large thesis for her nurse's education, and proved by the very good grade that she isn't. (And she has completed three educations the last twenty years due to changes in the need for labor.)
The situation is pretty desperate. Of the estimated 6000 languages currently spoken, one dies every fortnight. Even in the US there are eight languages ready to die with their last practitioners. Totally there are 48 languages with one last practitioner remaining, world-wide. Within 100-200 years half the languages spoken today will have disappeared. We can't hope to save them, but there are about 3000 "robust" languages which will survive the next 100 years, and equal access to technology for all of those are paramount.
Of course, a lot of problems also stems from the antiquated, and patently Anglo-file, ASCII which is still in use. Only last year a Sami (lapplandish) keyboard layout where completed, because the Sami special characters weren't available (together) in any current layout for Windows.
That's why open source is a vital factor in the preservation of languages currently spoken today. Please take care to use tools which enables internationalization of your software, it might seem trivial, but for many people it is worth much to be able to use their language in all parts of their lives. To communicate with the rest of their society through both spoken and written communication.
Here is a report named A Report on Improving Library and Information Services for Native American Peoples from US. National Commission on Libraries and Information Science from 1992 taking the needs of Native Americans very seriously.
Endangered Native American Languages: What is to Be Done and Why?. An article by James Crawford, 1994.
Finally I want to draw your attention to David Crystal's "Language Death". All proceedings from that books goes towards linguistic field research, it is a well founded book with a lot of good anecdotes.
Paul K Egell-Johnsen
zez.org: about code