It's not wrong neccessarily, it's just there's some issues with 2.5 RC1 and the way it handled some of the variables in the definitions. So the definitions for 2.5 had to be tweaked in a way that 2.0's definitions didn't need to be. Not to mention, the whole point of running 2.5 is take advantage of the global sizing options in the AME CP, which will only work with the definitions especially made for them:
DJ's AME (Auto Media Embedding) XML Media Definitions for AME 2.5