I guess we have Steven Soderbergh to thank for that. 

And the digitization process.

The big change that digitization made was it made it much easier to apply a single color scheme to a bunch of different scenes at once. The more of a movie you can make look good with a single scheme, the less work you have to do. Also, as filmmakers are bringing many different film formats together in a single movie, applying a uniform color scheme helps tie them together.

One way to figure out what will look good is to figure out what the common denominator is in the majority of your scenes. And it turns out that actors are in most scenes. And actors are usually human. And humans are orange, at least sort of!

Most skin tones fall somewhere between pale peach and dark, dark brown, leaving them squarely in the orange segment of any color wheel. Blue and cyan are squarely on the opposite side of the wheel.

You may remember from preschool that “opposite” color pairs like this are also known as “complementary” colors. That means that, side-by-side, they produce greater contrast than either would with any other color. And when we’re talking about color, contrast is generally a desirable thing.

TV Tropes’ entry on orange-and-blue color schemes pointed out that, while it might not be naturalistic, the color combination packs a semantic punch:

"Unlike other pairs of complementary colors, fiery orange and cool blue are strongly associated with opposing concepts — fire and ice, earth and sky, land and sea, day and night, invested humanism vs. elegant indifference, good old fashioned explosions vs. futuristic science stuff. It's a trope because it's used on purpose, and it does something."

It seems plausible that, regardless of whether or not it has its origins in color theory, orange-and-blue has now reached the level of “convention.” For better or for worse, coloring your movie this way makes it really look like a movie.

Like this:

http://tee.mybigarchive.info/post/42641/margaery-is-fire-and-tommen-is-ice-oathkeeper-s4e4

Ha, that's a Ukrainian copy of a PandaWhale page. In Soviet Ukraine, web copies you.

Some of the over the top colorized movies?

Pleasantville

Traffic (the original blue and orange film)

Sky Captains

And the most awesome blue and orange one?  Sucker Punch

Holy smokes. Cannot unsee this phenomenon now!