... If we consider photography to be an art, why should we have to adhere to the notion that the artist cannot inject his/her own ideas into the image?
I do not think that anyone here said you can not or should not. Certainly not me. As I already said in post #2: I often introduce myself, and only half-jokingly, as a photoshopographer™.
My photographs, landscapes included, are often heavily photoshopped. Some are visibly so, some barely perceptible (at least to an untrained eye). One of my most photoshopped ones, where I spent countless hours manually blending two exposures, dodging and burning, and countless other local adjustments, turned out to be one of my most successful ones, ending on a cover as well. And yet I rarely got a question: "Was it photoshopped?". The closest comment to it was that it looks more like a painting. I like to believe that is a consequence of my quest for "believability", while manipulating a photograph. Bass Harbor Lighthouse
by Slobodan Blagojevic
, on FlickrDigital Photographer Cover
by Slobodan Blagojevic
, on Flickr
In other words, it is o.k. to manipulate an image, even heavily so, but we then cross into entirely different categories of photography, ranging from fine art to digital illustration, or to use examples, from Ansel Adams to Bert Monroy.
And not only we are talking about different categories, we are now talking about different classes of buyers too. Those who are excited by unspoiled nature, rare natural sights, unique natural beauty, are predominantly in love with the nature, not photographic art. And they want their nature presented with no or minimum manipulation (the likes of Peter Lik, Tom Mangelsen, and Michael Fatali). And apparently they are willing to pay millions for it. No matter what you and I think, whether Ansel is greater artist/photographer than, say, Peter Lik, buyers are voting with their money. We can argue until blue in the face that there is no reason why a heavily manipulated image should be less valuable, buyers apparently think otherwise. To use an example from the world of movies: is the biggest box-office hit of all times at the same time the best movie ever? I do not think so... but it did make the most money.
At the same time, there is another class of buyers, that would rather gouge their eyeballs out with a plastic spoon then put "yet another pretty mountain sunrise" on their walls, photoshopped or not. They would go for a different type of photography altogether (if at all).