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.
I just want to say... thank you very much for your reply! Good to see devs and mods starting to address some of the things being brought up, we need more of this involvement from you guys.
EDIT: FYI, I think the main issue with smash is the ridiculous auto-crit, which enables the player to stack surge and power and have big smash numbers.