As long as we have a supported operating system WUBI should be supported, endorsed and advised (but with other options as being better) as a valid method of using Ubuntu. 

Even the download page still gives the option to use it http://www.ubuntu.com/download/desktop/windows-installer :

>With Wubi, **our officially supported Ubuntu installer for Windows**, you can install and uninstall Ubuntu easily and safely. For 12.04 LTS only.

>Windows installer is not compatible with Windows 8 or UEFI firmware, and is not available for Ubuntu 13.04.

As long as that page exists I disagree on us stating WUBI should not be used anymore. The disclaimer above is more than enough. 

Until April 2017 questions about WUBI are on-topic; a statement on the landing page will not stop those questions.

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Update: wubi seems to be valid again for 13.04: https://askubuntu.com/a/330112/15811 
( http://releases.ubuntu.com/13.04/wubi.exe )