All the planets are equally important in a horoscope. If you consider the life as a revolving disc, Lagna is the fulcrum and the offset from centre of the disc is what causes uneven revolution of the disc which causes us trouble. The planets are placed in the circumference of the disc at various places. So Lagna is the most important in a horoscope and Rasi is nothing but one planet Moon and you cannot treat it as something special.
Read my blog navagrahastro.blogspot.in for more details.