The ability to create a version 'On the fly' is introduced in JIRA 6.3. However, only Project Administrators can perform this action. If a normal user is creating the issue, they won't be able to create new versions while creating issues. The same goes for Components. This is because only Project Administrators can create Versions and Components in the first place.

One of the features which is going to be implemented by JRA-3156 would be for other roles (eg. Project Developers) to create Versions. This would mean that these roles should be able to create versions 'On the Fly' as well.

Since other roles can create versions 'On the Fly' it would be great to have an option to define exactly which roles can perform this and which can't.

For example, if I give Project Developers the ability the create versions, it would be because I (as administrator) am not the one which needs to create them. Therefore I should be able to configure such that only Project Developers can create versions 'On the Fly' while Project Administrators can't since I'm not the one handling them anyway