If you want to contribute actual changes to the Drupal software, you have to do it through patches. Patches are a kind of text file that describe the changes in a way that lets them easily be applied to the official code base. To create them, you have to jump through a couple of hoops, especially checking out Drupal head from CVS and creating the actual patch from the changes you made.
“…Surgical teams that follow a basic checklist in the operating room, from discussing expected blood loss to confirming the patient's name, reduced the rate of deaths and complications by more than a third.” (source)
Drupal module development will hopefully not cost human lives one way or the other. But when building your module's UI the same principle is at work. It's all too easy to skip the basics, and go straight for the more complex parts of the problem. That’s the interesting part after all.