Well, honestly I'm trying to assume positive intent on Blizz's part right now (which can be difficult at times).
It seems to me that Blizzard is trying to find a way buff rogues for PVE without completely skewing everything else. Let's face it, rogues are pretty damn buff in PVP at the moment.
The new blue post today suggests that they are going to keep HfB pretty much the same as it was before, but to have a prereq that there is a bleed effect on the target (from any source) in order for it to function. This is, in their own words, to discourage it's use in PVP. Theoretically, I can't think of any raid situation where a boss doesn't have bleeds up on it the entire time.
The buff to slice and dice would suggest the same thing. They want to buff us for damage over a long period of time. Also, their theoretical goal is to give people a choice. They don't want to kill muti in favor of combat, but to attempt to make them equally viable. This is a neverending questt.
So, these changes all in all seem to be working towards a goal of giving us the goddamned desperately needed buff for PVE, without making us so broken in PVP that we will never get anything done again due to the all caps QQing from every other class.
I know I am going to miss the pretty gigantic yellow mutilate numbers, but I'm hoping this is for the best.