(In the year 2010 we may not have flying cars, but we have ACTUAL piano neckties, with more processing power than twenty Apple ][ computers, which play actual piano notes when touched, and cost a mere ten bucks. Pwned!)
Apparently some designer early in the 1980s tilted their head to the side and thought, "You know, a necktie is kind of the same shape as a piano's keyboard." Except not really, because a necktie is necktie-shaped with points at both ends. A necktie is also longer in proportion to its width than a keyboard.
This width problem was exacerbated by the fad for skinny ties. You combine a skinny necktie with a piano keyboard pattern, and you're in for a lot of trouble.
One reason the piano keyboard design was appealing at the time was the fad for bold, linear graphics. Black and white was a very popular color combination, as well. You take a design with the strong bold lines of a Mondrian painting, couple it with the black and white color combination (seen in everything from Italian design to zebra stripe leggings) and you had a winner.
Keyboards were also very much in the public consciousness thanks to the rise of New Wave music, which put keyboardists front and center in the burgeoning electronic music scene. And let us not forget the wearable synthesizer, which could be wielded with the same amount of bravado as an electric guitar.
It makes sense, then, that a keyboard pattern would become popular. But why, for pity's sake, in necktie form?
The 1980s saw a lot of young men trying to break free of the fashion constraints of the past. At the same time, if you didn't want to look like a preppy Republican, you didn't have many options. New Wave was one of the few fashion choices left, and it had the tongue in cheek sensibility that today we associate with hipsters. The 1980s saw not only the piano key tie but the "t-shirt that looks like a tuxedo," and the "necktie painted to look like a fish."
Things that look like other things: how droll!
Men's New Wave fashion choices spent a lot of time playing with the Republican "suit and tie" conventions of dress. Think of the New Romantic look, which paired a black suit coat with a frilly shirt underneath. Not to mention the fashion for rolling back the sleeves of a suit jacket into cuffs, a fashion seen from A-Ha's breakthrough video "Take On Me" to Miami Vice.
Then there was A Flock of Seagulls, of course. For what that's worth.
Strangely, out of all the crazy-ass fashions of the 1980s, the piano key necktie has become an icon of the time. It remains a sentimental and/or tongue in cheek favorite, from contemporary artwork to Halloween costumes - and the piano tie was even name-checked in the 2001 movie "Zoolander" when Zoolander's rival Mugatu bragged "I invented the piano key necktie!"