Wow, haven't posted for ages but this one brought me out of the woodwork. Even the folks posting for the right reasons here can't seem to help jumping too far one way to refute the ignorant DNR fans' point.
Yes, 300 was shot on film. The actual reason? The amount of speed-ramped footage. Digital cameras may give you a nice matte, but they sure can't shoot at photosonics speeds. Nothing to do with 'obvious' greenscreen at all. The whole thing was so processed and stylised to match the look of the graphic novel that opinion is sort of redundant anyway. It was never intended to look realistic. Yes, I was there, although I didn't work directly on that one.
I'm sort of a bit dismayed that Spielberg is about the only person anyone can think of for examples. Surely a much better analogy would be modern horror movies in general, as Predator is absolutely a horror/action film.
The reason people like Taffy are being taken to task as ignorant is that they have no understanding of the process and thinking directors and storytellers employ (at least judging from how they articulate their viewpoint). And for someone with that handle, they really should investigate a bit more about their favourite film, Blade Runner. Let me put this as simply as I possibly can. Emotional logic generally takes precedence over plain vanilla logic in film, which is why as much as I love AVS and Xylon especially for his invaluable service, people here sometimes miss the forest for the trees in terms of intent or what is 'right'/appropriate. The Snow Walker sequence in Empire for example is one of the stupidest scenes of all time from even the internal logic established in those films. But one of the most brilliant from an emotional, figurative point of view.
Modern horror movies have access to equipment where grain is an AESTHETIC decision. It's about MOOD and an appropriate visual representation of the tone of the story. Grain is employed heavily these days as an artistic choice. Simply put, grain is being used to make these films GRITTY, literally AND figuratively. How does a plastic, scrubbed look generally associated with digital extreme sportscasts convey a dirty, grimy, squalid quality that puts you in there with the demented killer? Or vicious Alien hunter, as the case may be.
Although at the time the original Predator was made it was more of a consideration, it still wasn't a tiny budget. Arnie had already become a star, and the budget was equal to Aliens which was about the same time, but MUCH more ambitious with the same budget. So while this whole issue can't be truly settled until the director gives his take, there are a MILLION precedents for directors using film grain for exactly these creative reasons. And like someone already said, decades before there were things like 70mm. If you wanted less grain, you could get it. Even then.
To get more technical about it, film grain IS a chemical/technical side effect of film. If it wasn't, Kodak and others wouldn't have bothered to reduce it/improve grain structure/light sensitivity/film speed over the last century. And it is also true that the detail captured in the chemical/exposure process means the grain IS the detail and cannot be separated as if they were two disparate elements.
BUT for a long time now directors have turned what was a limitation into a powerful storytelling tool. In the same way as even further back, black & white film was a limitation and colour not possible. However the many directors and cinematographers and students of artists like Gustave Doré turned that supposed limitation to amazing strengths in achieving effects and storytelling potential colour could NEVER accomplish. Same goes for silent movies vs sound. There's a rich history of technical limitation turning to creative innovation.
In the same way as grain is used to cast a literal patina and figurative mood over a picture for the purposes of VISUAL storytelling, the advances in digital processing or film grading over the incredibly limited optical process have actually allowed filmmakers to achieve something very ironic- a return to almost black & white filmmaking. Sure it's all a blue wash, or a fiery red frame or even a burnished (almost sepia) brown, but they're using the powerful freedom of the new tools to stylise the frame down to an essentially monotone and therefore B&W tone and mood. Using colour to get effects only B&W could previously achieve. The overriding point being that in modern film these are no longer budgetary but creative decisions. And so the blu-ray or film can be exactly the author's intent. Double-guessing technicalities that are the result of creative decisions is a dangerous game, and the AVS regulars are right to stick to accuracy meaning true to the original theatrical intent. Not some idiotic tail-wagging-the-dog "make it look like the other stuff on my HDTV" backward viewpoint.
Finally, getting back to Predator, let me reiterate that it's dangerous to talk in absolutes. A big technical consideration with this particular film is the effects. The way optical visual effects work is that the compositing process is essentially a string of double-exposures. And the more multiple exposures you have the more degradation of image because you're losing generations each time. So if there's a decent amount of film grain in your stock to start with it'll get marginally worse each step. This is why many effects films used Vistavision which was for all intents and purposes 65/70mm stock. Much more negative space and therefore much finer grain. So when you go through your process hopefully you'll still end up with decent imagery on par with the live action stuff you shot at the lower-quality 35mm level. Now, where Predator is concerned, the signature effect was an invitation to lousy image quality. Concentric/freznel effects where the exact same imagery is reduced and placed over itself many times is a textbook example and perfect analogy of the Chinese whisper effect I'm talking about, image-wise.
So in this film's case, whether it was to give that appropriately 'gritty' feeling AND ensure less jarring change between the live-action and effects, the use of grain is entirely appropriate. And has a million precedents.
So yes, grain IS a technological/chemical limitation. And it is ALSO intentional. Both can be true at the same time. It's just that when people mistake one for the other or can only hold one point of view/black or white/ on or off (ironic digital analogies intentional), that the trouble starts. And studio marketing people have an astounding ability to judge things the wrong way. Third time lucky?
Sorry for the rant. That was a BIG two cents!