Rejected plugin

We have worked our butts off to make a plugin for some months. We did have a working beta version last year but we didn’t want to add it as a plugin until we was finish with it. Some days ago we thought it was ready for public and signed up to get it included at ww.wp.xz.cn as a plugin.
There is some other plugins in the same area for download so we was very suprised to recive an email that told us that “The plugin is not suitable for inclusion. It is not a good fit for what our users want.”
We have try to find anything that our plugin make to go against the few restriction WP have setup but can’t find anything. So how can our plugin be not suitable?