On CTAN, the package named "Comprehensive" contains a version of The Comprehensive LaTeX Symbol List dated 09 November 2009. But the corresponding package on MiKTeX contains a version of the file from 3 January 2008. Why doesn't MiKTeX reflect the latest version on CTAN? Can this be fixed?
Your first question can only be answered by the MiKTeX maintainer Christian Schenk. You could report this issue on the MiKTeX Bug Tracker, which should answer your second question.