I am an academic, with about 25 scholarly publications, depending on how you count them (see http://www.miketaylor.org.uk/dino/pubs/ for a list and for links to download them). I am here to tell you that we DO NOT GET PAID for writing papers (which, much more than books, are the primary medium of research in the sciences). Of the 25 listed papers, I got paid something for one of them, which was not really research but activism -- and I was paid by the acdvocacy group, not by a publisher. For some of the papers on the list, _I_ paid the _publisher_: this is not unusual.

There is literally no downside for an academic author to have his or or her work made freely available to the world: only the considerable upside of greatly increased visibility and influence -- which is the true currency of academia.