saving endagered languages

Here is a time condensed version of a thought process that has gone on within me over the past several years:
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Endangered languages why should we save them and how should we (as linguists) argue our case for the grant money necessary to do so?

Typically I'm PRO doing our best to revitalize languages that are on the verge of extinction. But this hardly ever works, so at the very least, I would hope that we can document/record/study in detail the moribund language for posterity. But why?

When I was a naive undergrad I felt that the biggest reason for doing our best to save or document these languages was because they are the best medium for transmitting the corresponding culture. It seems to me that this is the best argument to make if you want to get funding for such a project.

But then I thought: "should we force a minority population to keep their language alive if there is greater economic benefit for them to adopt the regionally dominant tongue?" And of course, the answer is no. So if there is a demand in the culture for learning materials, that demand should be met. But if there is no demand, then all the funds should go toward creating the very best linguistic database the remaining speakers can provide.

But then I thought: let's assume someone goes ahead and records a bunch of interesting data from such a language. Who actually goes back and looks at that data? Not many people... Sometimes you get news stories of grandchildren of speakers of some language reconnecting with their ancestors via the use of recordings of the old language (this generally leads to tears with a mixed bag of proud feelings and guilt over being so disconnected from your past - which all makes for good radio or tv programming). And that's a great use for them. But do linguists make use of the tapes?

Where am I going with this? Well, I think the real important reason to document these dying languages is so that we have records of the types of languages that exist - a more complete typology of the world's languages. I think this is important because I think that languages are the best window to the inner-workings of the brain, and the more such windows you have, the better you can see what's going on in there. I thought maybe, when we ask for money to document languages, we should mention this as being important. It turns out that nobody in charge of giving away money really cares about that. It's a stronger argument to say that you want to preserve the culture.

And then I thought, although the role of window-to-the-brain seems like it would ultimately be more useful, those long extinct languages for which we do have records are never really used for that purpose. Some syntactitians would have you believe that they are using them for that purpose, but I'm not convinced. But that's probably because I strongly disagree with the dominant views (in linguistics, if there are any) of what the brain is doing.

So what should we do about these endangered languages? I have no idea.