What's the reason for Canonical officially supporting versions such as Kubuntu, Lubuntu, Xubuntu, etc. instead of supplying the environments as Ubuntu 'flavour' downloads?
Why doesn't Canonical simply offer downloads of Ubuntu with different desktop environments?
For example:
Why not?
I see three reasons:
Community ownership of the projects - with a distinct vision
Having a unified "look" of desktop Ubuntu (that matches phone and tablet and TV Ubuntu) for marketing purposes
Canonical can focus its efforts on QA for one desktop environment versus multiple
The flavours are not simply Ubuntu with a different desktop environment. For instance, if you take an Ubuntu desktop installation and apt-get install lxde, you will have a very different computing environment than installing Lubuntu itself.
From Lubuntu.me:
Lubuntu is designed to be fast and easy to use. It has lots of applications for every daily need, while keeping your system light and responsive, being it ideal not only for old computers and netbooks, but for newer computers too making them lightening [sic] fast.
To that end, Lubuntu includes a set of packages and applications to perform typical PC tasks (office applications, media players, photo viewing and editing, etc) that are typically lighter-weight in terms of RAM and CPU usage than comparable applications in Ubuntu. (Abiword vs LibreOffice Writer, for example.) The focus is on low overhead.
In that way, the vision of a flavour like Lubuntu is fundamentally different from the vision of the Ubuntu Desktop project. For instance, two of their marketing points are, as stated on Ubuntu.com's desktop page:
Complete
Ubuntu comes with everything you need to run your organisation, school, home or enterprise.
[...snip...]
Looks great on the latest devices
Ubuntu is designed to work beautifully on the latest laptops, desktops and touch screen devices, it looks incredible on high resolution screens — and with touch screen enhancements and interface refinements including individual menu bars in each application window, it’s now even easier to use.
If Canonical wished, I suppose it would be possible to offer an LXDE spin, but if it contained the same packages and same amount of software, it would be far less usable on older hardware than Lubuntu is (which is part of the Lubuntu team's vision), and arguably take away from the unified, beautiful, modern experience that is important to Canonical's desktop marketing efforts.
I don't work for Canonical, but I have been involved with the Lubuntu community, and that to me is the fundamental difference I see between the projects.
Finally, as to quality: when I triage bug reports against LXDE packages, there are a number of unique and interesting bugs that happen when running LXDE on Ubuntu (apt-get install lxde on Ubuntu) vs. running Lubuntu. A lot of bugs that occur on Ubuntu with LXDE do not occur on Lubuntu. I'm not a developer, so I can't really help explain why, but for some reason the Lubuntu desktop is packaged and arranged in a way that makes LXDE work much better with Ubuntu than just installing the LXDE package.
The main reason is due to the contributions the derivatives make back to Ubuntu (as a whole).
...use Ubuntu as their foundation and contribute significantly towards the project
http://www.ubuntu.com/about/about-ubuntu/flavours
Those contributions are a mixture of community support, bug fixing and development.
Don't forget all the development, bug fixes, configuration for each flavour are all reusable (modular libs and components in particular) and installable in/from Ubuntu and all official derivatives as they share the same infrastructure.
The most important reason is to offer freedom of choice for users. Tastes differ and so do needs.Everyone should have the ability to choose what he needs or what he likes in good quality. Supporting various flavours will provide Ubuntu's widely spreading among as many people as possible.
Here you can see what kind of support a flavour gets after being recognized: https://wiki.ubuntu.com/RecognizedFlavors
Without these resources and services flavours would have difficulty in being provided in good quality to end users.
