Satellites are launched eastward so that earth's rotation can give an extra propelling force and we can save fuel which is a critical factor in the Rocket design. The earth is rotating in a counter-clockwise direction and when we launch our satellites east we take advantage of this momentum (angular momentum) from the earth's rotation. In effect, a rocket sitting still on the launch pad is ALREADY GOING EAST, at about 800 miles per hour!
However the statement is not completely true as few satellites launched to the south but this is a very small number.