If you want to publish your widget in our market place you can use the most suitable approach for you. You can provide the whole code for your widget or provide just an assembly including it. Keep in mind that when your widgets are published you will need to provide support for them.
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Sitefinity CMS Ideas&Feedback Portal
and vote to affect the priority of the items