I don't think the M is just for wealthy dentists etc. It just isn't a hard core PJ camera you would find in Syria or Afghanistan. Its GREAT for editorials. I rarely shoot assignments anymore, but when I do they are editorial portraits. I use M9s and a D800e, maybe MF film if I can.
Once upon a time, the Leica was a particularly well engineered "robust" camera well suited to photojournalism in extreme conditions. The same camera might give 20 years of service.
In today's "throw away" world where a camera is obsolete in a couple of years, such robust longevity is no longer appreciated the way it once was.
Photo journalists, like all professional photographers, have to consider the cost/benefit analysis of their purchases - unlike we genuine amateurs who can (obviously within the limits of personal budgets) splash money about to indulge our whims and fancies without any vfm considerations.