I'm going to start somewhere odd. Bear with with me. Or not. Your choice.
The ecology of the planet is complex. Like, ridiculously complex. There are vastly long looping chains of causality all through it. Arguably it is entirely composed of vast looping chains of causality.
There was a time when we were pretty sure we had a handle on it. We thought we'd be able to control and manage it, run it on scientific principles to the greater benefit of man. Then Rachel Carson and DDT happened (as well as a bunch of other similar people and events). Turns out that when you knock back some bugs all the goddamned eagles die. Say what?!! Then some math geeks started talking about chaotic dynamical systems and we realized that we're pretty much stuck with unintended consequences and that we probably could lose the whole planet with a misstep.
The whole thing's pretty resilient, to be sure. It's really unlikely that losing all the apex predators is going to stop plants from photosynthesizing. But golly, if they do things are gonna get real ugly. What's alarming here isn't that it's all fragile -- it's not. What's alarming is that we have no way of measuring, a priori, how large of a change will be wrought by, well, but pretty much anything we do.
Anyways. The point here is that these complex systems have unpredictable behavior. Small changes of inputs can cause large and surprising changes in output.
Now, consider photography.
It's profoundly human, whatever it is, in this sense: show a photo of a tiger and an actual tiger to a human, to a horse, to a housefly. The latter two are not going to get much if any "tiger-ness" from the piece of paper, but they'll probably give some distinctly tiger or at least mammal related reaction to the real thing. The human however will identify many characteristics in common between the two objects. Also, some important differences. Along another axis we can consider the underlying reality of the photo versus a drawing and so on. All that stuff I have talked about now and then, and wiser heads have talked about for decades.
Taken in total it's reasonable to treat photographs as, essentially, objects which have meaning in the context of human psychology, neurology, and sociology. Outside the whole gestalt of humanity, they're just flat pieces of paper. Inside it, they're infernally complex, potent, fraught.
You know what the gestalt of human emotion, psychology, community, neurology, shared memory and experience, etc, is? Yep. It's probably a chaotic dynamical system. Endless looping chains of causality.
So we switch from film to digital.
This changes the details of the ways we work, which in turn changes who does photography. People have left the field simply because they can't reasonably work with film any more (F. Evans, the other Evans, famously left photography when platinum paper became commercially unavailable). Loads of other people have entered the field. The process by which we make pictures has changed, has become more accessible.
Also, the physicality has changed. There isn't a physical piece of film anywhere. Pictures today usually have no physical manifestation, existing, always, as a pattern of signals which need to be interpreted by software and rendered by some light emitting system before our eyes can grasp them. This is an interesting fact, but it's not instantly obvious what the impact of it might be. But it is certainly true.
There are probably other aspects that have changed. Seemingly trivial and unimportant, like the loss of the physical negative. Obviously monumental and paradigm-shifting, like ubiquitous camera ownership and photo sharing.
All this crap gets dumped into the chaotic dynamical system which is humanity and humanity's perception of, relationship with, the photographic image.
Anyone who claims that these changes are trivial, or even that they or can predict understand the consequences, is full of it. He's just not thinking, probably because he doesn't care. Most likely he doesn't care and doesn't think because he frickin' loves screwing around in photoshop, and is under the impression that the whole discussion is basically a personal attack, probably because he's worried that his penis is abnormally small.
It's early days yet, we've only had universally available digital cameras for a handful of years. What happens when a generation grows up to adulthood, starting from 2011? What does photography look like then?
It's not a bad bet that something so small we don't even notice it today is, 30 years from now, seen as easily the critical factor, the important fulcrum upon which turned the changes to.. whatever the new thing is.
In short, the "eh, it's all the same stuff, just more convenient, why look, they've been manipulating photos since the beginning!" crowd is a bunch of reductionist idiots (and I bet if you dig through the archives of this very blog, you will find that I too have worn the reductionist idiot hat!)