I would imagine that the art style used in playing cards derived from the inability to create symmetry as easily as we can today (though in any complex design symmetry is still difficult to accomplish).
Keep in mind that they wouldn't design the entire back. It would be much more logical in my opinion to design a quarter of the back then mirror it horizontally and vertically. Or design half the back and mirror it vertically.
How easy do you think it was to "mirror" any design using 1885 technology? I get the feeling that it just wasn't too simple. Even with a computer these days some would find it a bit challenging - you mentioned your own protodeck symmetry issues on another topic around here somewhere.
Just as a guess - you could design a quarter of the back, copy it to a silkscreen, and through placements and flips as needed, create a sort-of symmetrical design. But then how do you get that made? Weren't printing plates still hand-crafted for anything that didn't utilize movable type? If you look at the old-timey decks that have hit the market (Bicycle 125, any Bee deck from CARC), the front and back designs (fronts especially, but also the Bike 125 backs), which are largely faithful reproductions, look practically hand-drawn! A lot of decks from a decade or two earlier had some of the simplest card backs imaginable - a simple cross-hatched pattern of lines, or little stars or dots or whatever in a simple repeating (and not always symmetrical) pattern. The challenge to make the classic card backs back then must have been huge to say the least.
