As you say, it depends on the content. And the content also not only describes the author, but also the user.
So if I am writing a page that is mainly read by newbies who are not even aware that their mouse has more than one button, or that you do not have to double-click on a link to open it, they might appreciate that they can always click something within the window to get further, and not have to go back from anywhere. (The fact that there are more newbies on the net today than xperts surely is no news for you... :-)
If I am smart enough as a better user to click the \"open in new window\" (one of the major reasons I am using opera for example), I should also be able to remark that the browser opened a new window, and deal with it accordingly.
The view on the point is surely difficult. I simply think that the maker of a site should be able to decide for himself how he wants to treat the user. if the user is not happy with it, he will leave and thus punish the user anyhow.