The requirements list will be most likely eased later on - IIRC it was also the case for virtually all major versions of Windows. The reason of this strictness is usually lack of testing or some compatibility features not being completed by the date of first release.
My guess is that they don't want people to blame the OS for their slow machine... I seem to remember reading years ago that vista was a victim of this (no way I can find that reference now though).
