They're intellectuals, after all, and intellectuals ought not to have to concern themselves with such things. That's a stance that's no longer tenable. The Internet has made it so. This can sometimes create tensions between universities and professors, tensions that can get in the way of implementing technologies that enhance teaching. More accurately, they didn't care about it in the teaching aspects of their intellectual productivity.
Professors write books and articles, and they teach.
It's always been the case that a professor's writings were considered their own product. Even if professors write their books and articles on university owned computers they would not think of assigning any ownership rights whatsoever to their employer. Similarly, if a professor were to take her lecture-notes and work them into a book, everyone would be outraged if the university tried to claim rights of ownership over the work. The advent of internet-based distance learning is presenting clear and present dangers to professors' traditional relationships to their work. Some universities are claiming that they own any electronic materials that professors put up on university servers.