The Grammy Awards staff came to the consensus that the current system was outdated and needed to be modernized.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:
It was deemed most appropriate to look at the more mainstream fields as a group, as well as individually. The desire was not only to tighten the number of categories in general, but to create a sense of parallel structure among these fields. For example, it was determined that each should have four categories in total. As to specifics:
Pop: Though the sheer number of entries made it difficult to fathom at first, the decision was to eliminate the distinctions between male and female solo artists and between collaborations and existing duos/groups. In the track categories, there also now is no distinction between vocal and instrumental performance, though it was believed that this distinction was still important in the album realm. Pop Instrumental Album remains relevant due to its breadth and inclusiveness of popular instrumental forms.
Rock: In this field, to get to the four categories that make the most sense, the distinction between solo and duo/group performances was restructured. Four-fifths of rock acts are groups, and even solo rock acts tend to be backed by a band. As the distinction was often hairsplitting, Hard Rock and Metal were combined. Due to a waning number of entries, Rock Instrumental was folded in with the other performance categories.
R&B: As with pop, male and female categories were combined. As with rock, solo and group categories were combined. Furthermore, what made most sense to the R&B expert members of the subcommittee was to maintain the distinction between R&B and traditional R&B in the performance (single/track) categories, but to combine Contemporary R&B Album and R&B Album.
Rap: The only change here was to fold the solo and duo/group performance categories into one, as with Rock and R&B. Most entries that had lived in the duo/group category were collaborations between solo artists. Country. Again following the leads from the fields above, the male and female performance has been consolidated, and collaborations now go to the duo/group category. Country Instrumental was eliminated both due to the exceedingly low number of entries and the move of Bluegrass Album to the American Roots field (which bars bluegrass tracks from being entered here).
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.