Let me start with the setup. General audiences love new movies, but they actually seem turned off by older movies, and the older the movie, the harder it is to get them to watch. For example, you would have no problem convincing people to watch a movie from 2012. A movie from 1992, however, would be a different matter. And forget a movie from 1962 or 1952. In fact, if you took a room full of people and you asked them which movie they would like to watch, even if you told them the 1962 and 1952 movies were the best, they would still overwhelmingly choose the 2012 movie. Fascinating.
So what is going on?
Well, tryanmax came up with some excellent ideas, which I will address as they arise, but let me start with this. Choosing a newer movie is the rational choice. Why? Quality assurance. Seriously. Humans can minimize their chances of making a wrong decision by going for the newest possible product that is available. I think similar logic applies to their selection of films. Consider the following three reasons why people view "new" as an indication of quality.
(1) Depreciation: Think about cars. People prefer new cars to older cars. We know this because new cars cost more. In fact, take the extreme example. You have a brand new 2013 Ford POS with less than 10 miles on it. By happenstance, the dealer just happens to have an identical unsold 2012 Ford POS with less than 10 miles on it. The 2012 will be worth significantly less than the 2013 even if it has the same body, color and options. Why is that? Because people assume the new car is of a higher quality, even if they are identical. Does this make sense? Well, yeah. The 2012 has a year's worth of corrosion on it. Its rubber is a little more brittle. Its paint is a little more oxidized. And if you try to sell it down the road, the buyer won't care that you bought it new in 2013, they'll only see that it was made in 2012. This is the same reason you pick out milk or fruit with the newest date on it, even though you plan to eat it long before the date passes: products depreciate over time.
But do films suffer from depreciation? Yes, they do. Like cars, films "age." And by age, what we mean is that everything about the film becomes less relatable in the present. The clothing, the dialog, the slang, the types of cars and homes, the things that matter to the characters. Tryanmax called this "creating a temporal distance," and I think that's very accurate. And the further back in time you go, the greater the temporal distance and the harder it becomes for modern audiences to relate. Thus, for example, if you don't own a leisure suit (or even know what one is) or if gas is plentiful, then a film set against the fuel shortages of the 1970s have a hard time feeling real to you. In the modern world of the US's dominance, a 1960s thriller about the Soviets taking over the world might be hard to care about. A 1930s film about a floozy in a speakeasy might seem like utter nonsense to you.
Films age because society changes, and the more society changes the harder it will be for most people to put themselves into the world they are watching, and that means they will enjoy those films less. By picking a new film over an old film, the average person all but guarantees they won't encounter this problem.
(2) Innovation/Improvement: People also prefer new things because new things are more innovative and tend to be technologically superior. Consider medical books or science books. Those depreciate in value very quickly as human knowledge grows and these books become outdated. Products experience this too. Older sports gear is heavier and less protective. Older computers have less power. Older houses don't have all the modern features. Older dogs are harder to train, as are older foster kids. Everywhere you look, older is lower quality, and our society reinforces this idea in our idioms, in how we sell things to each other, and in what we value.
A related point is that the newest products generally have their kinks worked out. Always skip the first model year of a new model. Why? Because they haven't worked out the kinks yet. Wait until they fix the problems they discover. Similarly, most people are slow to jump on new products until the early adapters have helped work out all the glitches. This may be behind an issue I've noted with books too. If you are selling five books and they came out one per year from 2009 to 2013, you would be amazed how many people will happily grab the 2012/2013 books, but will flat out ignore the "old" 2009/2010 books. Why? Well, I suspect they realize that most authors need time to hit their stride. So if you want to get the highest value for your buck, you pick up the books that are likely to be the highest quality, and that would be the most recent because logic suggests that you need time to refine your craft. Practice makes perfect, after all.
Is the same true of films? Absolutely. Knowledge is cumulative. And over time, film techniques, special effects and story telling techniques have improved. The reason for this should be obvious: each generation of filmmakers essentially can take the best of the past and recreate it while adding their own innovations. For example, while it may have taken a real breakthrough for Orson Wells to decide to put ceilings on his sets, every filmmaker knows to do this today. Steven Spielberg taught us in Jaws that delayed gratification can increase drama. Quentin Tarantino opened the door to strong nonlinear storytelling. And so on. Each innovation goes from unique risk to just another tool in the toolbox. So if an average person wants a film that is most likely to be based on the highest amount of quality engineering and is most likely to have the kinks worked out, then a more modern films is logically your better choice.
And just a few quick examples can show why this is reasonable. Which has better special effect? Harry Potter or a horror film from the 1960s? Which has more realistic dialog? A film from the 1980s or a film from the 1940s? Which has a stronger score? A film from the subtle 1970s or a film from the 1950s where bombastic was the word of the day? Even story telling has improved because there are so many more tools now. Again, by picking the newest films, the person improves their chance of getting the most value for their dollar.
(3) The Herd: Finally, there's another aspect of the human condition that gets us to buy new things: the herd instinct. In fact, this is the most common form of advertising pitch - "Don't you want to keep up with the Jones? Celebrity X owns one." What this does is play on the human instinct to not get too far from what the rest of the herd is doing. This instinct exists in all aspect of consumer behavior, so it's logical that it exists in the selection of entertainment too.
Tryanmax made this point: "everybody just wants to see what their friends are seeing." Said differently, people may see entertainment more as a form of "keeping up with the Jones." That would mean that people are drawn to current films not just because they think they might enjoy them but so they can maintain their place in society by talking intelligently about the latest films and thereby demonstrating their herd-savvy. Consequently, since the rest of the herd isn't racing out to see Risky Business, there is a low value placed on seeing that film, certainly a much lower value than seeing the current blockbuster. And since human activity time is limited, older films tend to lose out because the time allotted to watch films is being absorbed by herd-fare.
Now obviously, the above ideas don't apply to everyone. Some people are contrarians and will actively avoid herd-fare. Some people are nostalgic for an era. Some people are film buffs and like different films for different reasons. But for the vast majority of people, films are not something they want to develop as a hobby. So when they decide to see a film, they simply want the film that is most likely to provide them with the best value for their time. In that event, it is logical for them to assume that a modern film will likely be more relatable, will be made with higher quality techniques, and will deliver a bigger social payoff. So it makes sense that they would pick the more modern films.