In all current versions of evolution: Seeing as there appear to be "no user servicable parts" inside, is there any reason to not hide the ~/evolution directory as ~/.evolution so it will not show up in nautilus and invite disaster (moving it to trash, for instance)
This will only get changed if it gets changed upstream. There are too many issues with migration and compatibility with upstream to do this. Additionally, the argument given upstream is that it contains your mail if using pop or the like and so should be user accessible.