You're right. Unfortunately, due to the distributed nature of open-source application development, making that sort of shallow usability integral to the whole system is very difficult. Until there exists an incentive for open-source developers to provide those sort of features, you either won't see them, or you'll get the patchwork quilt that the author was complaining about from Ubuntu.
The rejoinder is that wide adoption requires that kind of usability. It must be an integral feature of your application, or your app will remain ghetto-zed and obscure. That may be ok for some developers, but for most, usability must be just as key as functionality.