Adequately understanding retirement-age policies, trends, ethics, financing, health costs and benefits, and the stakes in debates about any and all of these presupposes having clear concepts of "retirement age". That's "concepts", because there is more than one concept of "retirement age".
As a preliminary to understanding and action regarding anything, it is always important, indeed highly advisable, to know what it "means", at least as a concept and its definition(s), if not also in terms of what its real-world implications are. It is all the more important when a seemingly transparent concept, like "retirement age", is actually a set of different and variable ones, however related, that are all of real importance, whether you are aware of them or not.
Moreover, whether you are at, near or far from retirement age, current and future policies, proposals and trends are going to strongly impact you not only when you retire, but also now and in the "golden" post-retirement "then". Otherwise, if you are a retirement specialist, having a strong grasp of the spectrum of concepts, trends and policies can improve your odds of not only keeping up with your field, but also of keeping your own job until retirement.