Why GPL is discouraging users? Is it the case that Drupal, Wordpress or Joomla have no users? They are all released on GPL terms. Moreover, they consider themes and plugins to be derivative work and as such they have to be released on GPL terms if distributed. Still, thousands of plugins and themes have been made.
Pay close attention here, *if* distributed. In common web development scenario where expected end product is the working web application deployed on some server, the application code is not distributed but simply used and doesn't have to be released on GPL terms. In those rare cases where client specifically require the source code as she wants to deploy the application on her own, you release the code on GPL terms but to her only. She paid for it's creation anyway right? And with web2py, thanks to exceptions, you don't even have to do that. Application code is not considered to be a derivative work. But changes to the framework and works build on top of it are (that is, *if* distributed). So again, you can have your own specialised version of web2py running on some servers, but you cannot make a proprietary fork of web2py. And this will be allowed by non-copyleft licences such as modified BSD licence or X11 licence. Now, those who would benefit from a proprietary fork are not the users. And in that sense, by not allowing the community fragmentation around a number of different less or more commercial oriented forks the GPL helps to create a good framework, as it keeps the community together. So as I just showed to you, GPL is a non-issue for the users and protects the freedom of the framework much better than non-copyleft licences would. Your only argument being "the other Python frameworks use non-copyleft licences" is not convincing. Statistic != merit.
