EDIT: Strikeforce got it right and picked up where Affliction went wrong. They consolidated their heavy weight division, cross promoted which is unheard of in the UFC with the exception of Chuck fighting in Pride, and ramping up the woman's division all without putting their eggs into one basket (Fedor.) Why else do you think the UFC bought it out. Strikeforce was a threat. I hope Scott Coker and Frank made out like bandits cuz they knew what the end game was the moment they signed the dotted line. There can be only be one.
They bought it out because Strikeforce put it up for sale. From what I read after the Fedor and Henderson deals and then after the big fight on CBS cost them the CBS deal. Investors were nervous and wanted out.