The two web pages mentioned in the reply were ones I had already read - last year. In them, Steven Sinofsky, president of the Windows and Windows Live division, explains the process of secure boot in great detail with some nice colourful charts, and also gives an overview of the additional security that will be available in Windows 8 compared to earlier versions of Windows.
They tell one exactly nothing as to why secure boot was adopted.
It seems reasonable to assume, thus, that Microsoft wants no part of any reasoned discussion on the issue and does not feel accountable to the public about what it does.
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