Hopefully i can say something relevant.
While the internet has helped spread this 'narcissism' it stems from the fact that 'doing things for others' (or 'what you can do for your country') mentality, has left many unsatisfied in their later years. Perhaps this has always been the case, since feudalism (did we even live a tranquil enough life to think on our lives and their value) gave little way to happy living. Nonetheless, the 19th century gave rise to a notion that has capitulated into what it is today. To broad to mention in a photography forum, i think there was a turning point with Hegel's Phenomenology of Spirit (i forget the german name) which led to a slow revolution in schools of thought. This led to the German Idealism which became widespread. Even though these philosophies vary there was clear deviation from previous philosophies in that they gave Individuals the Right of Reason, and to an extent their Reality. In the 20th century we see the more questioning of the church and a definite centralization in the individual.
If you've ever had the opportunity to read any Joseph Campbell books (i've only read the Hero With a Thousand Faces), myths/stories clearly become pathways for individuals to follow. While these paths are ritualistic in nature, and many cultures/tribes have their rules to follow, it becomes clear that it is there for us, to help us, find our 'life path' per se. So in essence it's become overtly clear that we live our lives not for others, or through others, but for ourselves. Yes, we can do things for others, but satisfaction comes from within, and this has clearly been know for as long as we have lived, regardless of whether we have negated it at some point or other.
The problem arises, when we relegate ourselves only to look within, and fail to 'find ourselves' and return to the world/reality. Many may feel this is silly, but i have to say, that seeing older people with many regrets is not something i want to grow into or up to in my later years.
While there is a clear distinction between this (finding oneself) and Narcissism/Egomaniacs, the 'arts' have always been seen as a cultures way of communication (sometimes abstract for en masse dissemination). While photography holds a reality, it also shows a perspective, therefore, it becomes a 'truth' but not just a simple 'truth' but a 'truth told by someone'. while a sculpture, painting, etc. might be based on truth, it's a given (or partially) that the artist has creative license to give it a twist, his twist. Photography for the most part, doesn't let you do this (Jerry ueslmann being our great exception), and so it becomes about the 'photogrpaher's eye'. Some still believe photography is not an art, i volunteer at a museum and was told this to my face.
Before i continue rambling
So to say that narcissism is emerging in photography, perhaps it is, but it's been doing so all around us (as in other fields of art, and in our culture in general) and has been doing so for centuries. Moreover, it's inherent to our life, because it's how we live our lives to an extent. I can see where you have a problem with egocentrism, but that's a psychological problem perpetuated by people with cameras.