Can be simulated by shooting at the same frame rate (24 fps) plus some post-processing? It probably wouldn't be simple to write an accurate simulation, and it could be quite GPU intensive to process, but I imagine it's possible to get results from a digital camera that are indistinguishable from those using film.
One instance where it's very obvious to me was 300 vs its sequel 300: Rise of an Empire. I tried to find 2 similar images: 300 http://www.dvdbeaver.com/film2/dvdreviews46/300_the_complete... 300 sequel http://ia.media-imdb.com/images/M/MV5BMTQwMTk3MTU3OV5BMl5Ban...
So basically I think digital is getting there but it still has a little ways to go in matching the perceived quality.
I guess it is quite subjective, but what makes the second one look better to you? For me the first one, whilst chalked with noise/grain, has a much better rendition of the skin-tone, along with detail in the highlights, and the depth of the reflection in her eyes. I guess it's hard to describe really, but that's kind of why I would side towards the first image.
The main thing is the noise on her skin - it makes it look very artificial. Like it's not an actual person. On her cheek it almost looks like she has beard stubble.
The background of the first one also looks like a pointillist painting instead of the real world. (Although I might not notice it in motion.)
I'm not a fan of the skin color either since real people don't look like that. To me it looks cold and artificial, like I'm looking at a painted robot instead of a person.
I do wonder how much of this is film vs digital, as opposed to post processing. Film might not be able to stop grain, but I don't think it needs to look like that for the color. It suspect it was over sharpened and over contrasted in post.
Although high-def video most often is used for blue screen shoots, director Zack Snyder and Fong shot on film. "We wanted the film grain to show," Fong said.
I'll add that I think that convenience and workflow is the #1 reason for the change. The cost of film and processing in all but small independent productions is a minuscule part of the budget.
It really is difficult to say what sets film apart, but it's generally agreed among cinematographers digital and analog that the filmic quality is pretty unique to the film itself, though of course it can be faked fairly well.
With film, color response varies by film, ISO rating, light source and exposure [1], so each one has a very particular character ("Kodachrome look", "Provia look", etc.). Also, analog media isn't prone to clipping, so you can get deep reds, deep blues, detailed highlights/shadows and still have the rest of the scene perfectly exposed without a lot of work.
It's hard to achieve the same characteristics with digital in post-processing because the limitation is at the capture step. It's like trying to fix a dull audio recording - no amount of work in post can bring up a frequency if the mic hasn't captured it.
[1] http://www.kodak.com/global/en/professional/support/techPubs...
This is all, of course, in the context of color films. Black and white films are particularly difficult to mimic with digital, partly due to spectrum rendition issues that are difficult to recreate in post processing, partly due to very different grain structure (B&W grain is generally sharper than the dye clouds you get with color films), and it must be admitted partly due to romanticism on the part of film partisans.