[billroberts]

"how do you get value from providing it" - how do you get value from publishing anything on the web? The same principles apply. The value comes from making information more readily available, so people can find out new things, make connections, do their jobs better. If you want to make money from it (and of course a lot of data has already been paid for by the taxpayer) then you can do all the usual stuff: charge for access, charge for services built on top of the data, provide it free and use it to build your brand or to gain attention of people that can be sold to advertisers etc.

One important use case is publishing data for re-use within an enterprise or other organisation - it doesn't necessarily need to always be public.