Bryan Magee, The Philosophy of Schopenhauer (1983):
Although professional philosophers nowadays are often highly skilled in matters of argument, it is in the nature of things that not many of them can be expected to have original insights. The outcome is hundreds upon hundreds of books which are well argued but have little or nothing to say that has not been said before. And because the quality of the argumentation is the only distinguished thing about them, and also the thing their readers as well as their writers are best at, it becomes the object of interest, and hence the criterion by which they and their authors are judged. In consequence, many professional philosophers and their students slide unthinkingly into proceeding as if philosophy is about arguments, and they lose sight of the fact that it is really about insights.