I want to say that the simple answer is that the project name is a part of the URL, so when you change the name, it changes the URL. I do not think this is a bug. I think the problem that you are referring to is that when you change the name of the project, you would have to update every instance of where that project was linked as well right?
In reviewing this internally, changing a project name should not change its URL. This is currently an open bug with Jive 8. The bug is still open therefore I do not have an ETA on the resolution. However if you would like to be notified when the bug is closed, feel free to create a support case in your Private Support group and provide them the bug ID JIVE-20075. This will allow Jive Support to associate the bug with your account and notify you when it has been updated.
Hope this helps.