Have you read David Foster Wallace's take[1] on this issue? To me[2] it seems like a good case for a form of prescriptivism. I do have to admit that I'm a huge fan of DFW and am surprised anyone was able to write an interesting article about the "linguistic wars", so maybe that colors my opinion somewhat.
[1] http://harpers.org/media/pdf/dfw/HarpersMagazine-2001-04-007... [1a]
[1a] PDF warning
[2] Someone with no background in or knowledge of linguistics