I asked Austin Peckenpaugh (Senior Designer) about Rage and Focus builds and how they're fitting into PvP overall right now, and here was his comment:
Rage and Focus have always been high burst specs, but they haven't been very popular due to some usability and quality of life issues in the past. Our goal for Focus and Rage was to address those issues without significantly affecting their burst. In large part, I think we've done that, but the result is that many people are playing them now, which means there's a lot of AOE burst happening in warzones that wasn't happening before. We're willing to wait and see if their popularity is a result of being viewed as "flavor of the month" (i.e. Rage/Focus populations will naturally subside as people realize the spec doesn't suit their playstyle) or if they are truly too good and were just too unusable before. In short, we're going to keep a close eye on it.
lol, standard fluff answer which exposed itself in the first line, rage and focus builds were not popular indeed, they were always the "stock" build, now every faceroller jumped on the ez mode train.
Oh and whoever thought the hardest hitting ability in the game should be a aoe should not be employed as a game designer.