Like Arthur Fry who create the Post-It at 3M, the best way to have your innovative ideas improved by colleagues is to make your idea real with a prototype, mock-up or the simpliest feature.
But don't feel too badly at having a good idea shot down. This happens to many clever people. Unfortunately, politics rule decisions in many companies. And as a new guy in this type of situation, you may have to build up some credibility before people will take you more seriously and possibly stick their neck out for you.