HDR imaging is a technique that is used in, to steal a term I saw a few weeks ago, computational photography. The whole idea behind constructing an HDR dataset is to extend the range of your camera's sensor in terms of what the camera's sensor is physically able to capture in a single exposure. Many scenes in real life have a much greater dynamic range than the camera is able to capture in a single exposure, a fact that leads to plugged shadows, blown highlights or both, without the use of extra lighting, etc.
When you shoot a sequence of exposures for HDR, you are doing so with the idea that you will use some math to assemble all of the luminance data in that sequence of images into a single, High Dynamic Range dataset that will consist of a single image that contains all of the luminance info from the multiple exposures your camera recorded.
These HDR images, or datasets, are not viewable in their entirety on traditional 8 or 10 bit displays, or printable on traditional printers, so one must tonemap the high dynamic range data into a low dynamic range result, again through computational methods and operations.
So, HDR photography is used to capture all luminance data in a scene, typically a scene where this data will far exceed the capability of the camera;s sensor to do so in a single exposure. Do people use HDR imaging as a crutch to ignore exposure? I can;t answer that per se, as everyone who tries it or uses it may do so for any number of reasons. Typically HDR imaging is used where it is important to be able to manipulate the full range of luminance - CG, compositing, photography, synthetic lighting, etc.
I would guess some use the HDR techniques in non-HDR situations. I would guess some use the HDR tonemappers on non-HDR sources to get that contrasty "HDR look". It all depends on your goal and intent.
For example, a typical HDR situation would be when you want to capture an interior with strong exterior light coexisting in your shot (say large picture windows or stained glass). Here you want to capture the full highlight data in the strong lighting areas as well as the full shadow data in the interior areas that are indirectly lit. The dynamic range of this scene far exceeds the camera sensor's ability to capture all of it in a single exposure, so highlights will be blown or shadows will be plugged, or both. Here is where you wish you had a camera sensor that could capture more dynamic range - until then we will use HDR computational techniques.
In a way, shooting a sequence of exposures is some insurance against mistakes in exposure (i.e., traditional bracketing) but HDR is different in that the images in the exposure sequence are combined to produce an image that would otherwise not be possible from a single exposure.
There are other techniques besides HDR combination to give you similar results, including exposure blending. Often if I am shooting in harsh lighting conditions, I will shoot a bracket of 3 images, separated by 1 or 2 stops each with the intention of combining them into a MDR (medium dynamic range) image that will be achieved by blending. For example:
https://photography-on-the.net/forum/showthread.php?t=610617
The bracketing was not necessarily used as a crutch or an excuse not to worry about getting the exposure correct, but rather a deliberate strategy to capture the image the way I wanted to, under the lighting conditions that were less than ideal for a single exposure. As you can see, I shot three exposures and blended them in LREnfuse, and then did my PP on that image. I got a much better balance of highlight and shadow detail and preserved most all of the critical highlight and shadow info for the final PP.
So, HDR is sometimes the optimal route, should the scene necessitate it. Sometimes MDR blending works better, especially when trying to avoid HDR tonemapping artifacts like haloing and color shifting. Sometimes there is no need for either, but, as the photographer, you like the effect that tonemappers have on a regular, single exposure RAW or LDR image and so you apply the tonemapper to get some artistic kind of effect.
In my opinion, one of the inherent benefits to capturing a scene with an HDR approach is that the sequence of images you shoot forms the basis for whatever technique you ultimately decide is best for the final image. That is, you may originally think you need to shoot a 5 image or 10 image exposure sequence to combine into an HDR - so you go ahead and take your shots, say each 1 EV apart. Upon review of your images, you may decide that the tonemapped HDR you create from that sequence is not expressing that vision you had when you were capturing the shots. The nice part is, you have a 5 or 10 image bracketed set of exposures of your scene that you can then go back and use to construct your final image - with whatever technique(s) you choose. Thus, in preparing for an HDR workflow you have captured a a lot of data that gives you flexibility in the creation of your final image, regardless of whether or not you produce the final image using the traditional HDR workflow.
Obviously, this all depends a lot on personal preference, etc. Some scenes simply don;t have a high dynamic range, so (mis)using an HDR approach may not give you very pleasing results, compared to the 1 or 2 shot, LDR approach that would yield a much better final image.
Blah blah blah.
have fun experimenting!
Kirk
