The Grammy Awards staff came to the consensus that the current system was outdated and needed to be modernized. From the 2012 Grammy Awards ceremony and moving forward, more importance will be placed on popular, mainstream genres of today. Here's their explanation:
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The staff goes on to explain that the less popular genres will keep the same structure they've always had, for the most part.
Are these changes for better or for worse? Only time will tell. View the other changes that were made at the official Grammy website.