I have been part of the Umbraco community for some time, and an active contributor to packages (All my packages code are on codeplex too). One thing that has REALLY helped Umbraco, and something that Niels himself (The creator of Umbraco) pushes is all packages should share their codebase (Codeplex or Gihub).
This helps new people or people who are not hardcore devs to see how things are made. Allowing them to maybe have a go at making their plugins/widgets. Other people can also contribute and help improve existing plugins, or help fix bugs on plugins that the owners just don't have time to do.
Considering nopCommerce is free and opensource, it really blows my mind that people who submit free plugins are funny about sharing code. Sharing code, helps the community AND it helps nopCommerce massively. I am almost up to speed now with v3 and intend on creating a few free and paid plugins. Just like I have done with my Umbraco packages, I'll be putting my free widget / plugin code onto Github/Codeplex.
I urge you all to do the same if you have free widgets/plugins that are used.
* Just my two pence worth *
