MSI was better known as a tier one Nvidia partner that drives most of the graphics business, but since market significantly changed in last few months MSI just could not stick just with Nvidia.
With Gigabyte and Asus doing both Nvidia and ATI, MSI simply could not resist the temptation to join its big brothers. Even though it makes things harder for the big GPU guys, that's competition.
Read more: The Inquirer.