Content that has had DNR applied to it actually looses detail and accuracy. Grain is simply an artifact of how images are captured on any given material. Film will always have some level of grain, for example Kodak is still actively refining its filmstocks that have even finer grain structure. It is still there but most folks find it less intrusive and some would interpret it as more HD when it's transfered to BD.
A good studio will clean up a master but will not apply processing like DNR because again you loose detail while you may gain a percieved increase of sharpness but everything begins to look pasty, waxy, and airbrushed.
Pan's Labrynth has some "Light" DNR applied and some folks don't mind it at all. Others claim it's so minimal that for the majority of >current< users they will never notice it. Of course people are progressively going to get bigger screens in their homes and will soon see this foolish manipulation and wonder why everyone looks waxy.
This type of argument is like the one over ten years ago for DVD. Why release in anamorphic Widescreen when the majority of users do not have a widescreen TV?
Thank goodness Anamorphic Widescreen became a standard so we can see the whole image and get better detail when we did buy an HDTV.
When people start making excuses for little distortions and manipulations like this now, one must ask the questions when and how is it too much.
Similiar to the music loudness war. Everything is too damn loud with minimal interesting dynamics thanks to gross over usage of compression techniques and the permitting of excessive clipping which looses audio information.
Give me my Volume knob back!
Besides just about every TV now a days have these "improvement" features then stack them upon already DNRed content and you get a double wammy of waxy.
Give me a clean transfer that is reflective of the original negative and let me be stupid enough to apply DNR myself.
Now if you have post processing turned on in your own video chain, that will make grain look very obnoxious. Too much sharpness applied and DNR will make film grain really stand out, rings and halos are artifacts of these settings which turns grain into a noisy mosqitoe like mess.
Personally I liken grain reduction/elimination to the defacing a painting or say the difference between a print versus the original.
Let's take the Mona Lisa for example. Sure anyone can get a nice poster print of the painting, yet people still actually go see the original. Why? There are numerous reasons, I think though apart from just the prestige of actually seeing it in person, people want to have more "tactile" experience and see first for themselves the hand of the artist.
A good poster will provide lots of detail but not as much as actually seeing the original for yourself. There is still no pratical way to fully recreate a painting to the last brush stroke but with HD it essentially can replicate the original source.
If someone didn't like all those visible brush strokes on the Mona Lisa and removed them you would loose the essence and uniqueness of that painting. It would be nothing more than all the other depthless duplicates.
Proper restoration is a different animal all together.
Don't Panic! Grain is just the nature of film, without it you wouldn't be watching anything in the first place.
Politics is like a corral, no matter where you are you'll always be shoveling it.