Why do more people study Japanese martial arts than Chinese martial arts?

I'm assuming you must live in the Western Hemisphere. The reasons that such a large percentage of the west favors Japanese Martial Arts are several. One is because most of the Japanese arts are of a more linear and less complicated form which favors the west's more aggressive and direct mentality. Another reason is that many military soldiers brought the Japanese arts back with them from their stations in Okinawa and Japan. The Japanese have, since the Feudal era, been willing to share their arts with the outside world where the Chinese have been very secretive about theirs. Much of the Chinese styles is still misunderstood by the west but with the internet and a more open Chinese mentality, you will surely begin to see more exposure...however it may not be adopted quite so quickly by westerners still. Best wishes.