Ultimately, it's the core reason Cata PvP has been such a trainwreck from season to season.
It's not so much that they've made some bad decisions here and there - no one's perfect - but that when a problem shows itself, they haven't really been willing to actually do much about it.
What I don't get is why they don't use the PTRs to test stuff like this. Rogues are suddenly OP due to scaling? Hey, let's try nerfing FW to 50% and see how that affects things. Too much? Hey, let's try 60%! Isn't that the point of a PTR? To function as basically an on-going small-scale beta?