When you author a book, you earn some money. Not a lot, perhaps, but some. When you author a journal paper, not only do you not earn any money, but you pay the publisher several thousands USD in fees! For example, Nature: http://www.nature.com/ajg/open_access_faqs.html. Even worse, you must sign a copyright form that transfers ownership to the publisher.
I understand that there is a staff behind the scenes that puts these publications together -- editors, admin. staff, etc. -- and they need to be paid. But some journals have acquired such prestige over the years that they can name their price, and the manuscript submissions will keep coming. So perhaps these prices are not so surprising.
In the debate over which makes the most impact -- journal vs. conference paper -- most academics will say the same thing: journal, journal, journal. That message has been beaten into our heads. But in my opinion, we are entering a new period of transition similar to what newspapers have been facing. I think it is possible that conferences and journals with new subscription models will slowly usurp a share of manuscript submissions away from journals with traditional models. For example, in ACM and certain IEEE disciplines, conference papers already reign as the preferred publication format among researchers.
Of course, in other areas such as law and medicine, there is probably no hope. Things will remain the way they are.