You're not the only one; astronomers have also been surprised. But you have to keep in mind that our data right now is very incomplete. Kepler only operated for four years. You'd need a minimum of three years to detect a planet with a one-year-long orbit. (The first two years give two blinks when the planet crossed in front of the star, and then the third blink should be exactly a year later.) As they analyze the data in more detail, they'll probably find planets with longer-period orbits, but possibilities are limited.