Matcha is unique style of green tea that has been used ceremonially in Japan and China for centuries. Tea has long been used in religious ceremonies and meditation. As a hunger suppressant and a caffeine fix, tea can aid in long meditation sessions necessary for spiritual development. Here is a great article from eater.com which shows in beautiful photographs and describes how matcha is prepared and served.
Fast forwards to today. The candy manufacturers have been able to succcessfully sell chocolates to East Asians but felt they needed the help of some evil genius to somehow sell more. According to an article written in the online magazine Japan Monthly, the ubiquity of matcha flavored products have only been around for the past 20 years. I will venture to guess that the trend started in fine dining circles and then only later moved on to the mass market. It may have been that creative chefs noticed that powdered tea, resembling something like espresso grounds, just might help reimagine classic dishes. It was a hit and so matcha flavor became the flavor du jour in fine dining. When that fad passed, we got stuck with it....forever. Today matcha is found in everything from Starbucks' drinks to the Kit Kat bar. A similar ploy is underway with exotic food ingredients on the savory side of the spectrum. Squid ink, found in Japanese noodle dishes, can now be found at Burger King in Japan sans white truffle.
The Matcha Kit Kat bar is a junk food in the purest sense. It is made with white chocolate, which is not really chocolate at all. White chocolate is made from the fat of the cacao bean--a bi-product of the chocolate making process. It is then mixed with sugar and milk solids to form an edible insult that floods your mouth with sweetness and forces your brain to register enjoyment. Only a strong flavor like vanilla or matcha can withstand the assault and leave a pleasant aftertaste in your mouth but it's not the taste of real vanilla nor the taste of real matcha.
Matcha Kit Kats are for people who want a chocolate bar but hate chocolate. They are for people who want to taste matcha but hate green tea. They are for people who want to eat something but perhaps hate food.