I'd make the case that visually, the channel looked much more like a slapdash college project prior to the 2013 update. You had, at that point, five years worth of differing graphics packages, many of them poorly done or very generic. There was no unifying brand, visual or otherwise. Simplified as the current package may be, it's incredibly clean, unified, and a distinct visual brand that they can identify with. To me, the current brand is a classic example of "less is more." Every icon, for example, gives you a very clear idea of conditions expected. Could a previous set with skeumorphic gradients, shading, and animations do the same thing? Sure. Does it need any of those things to serve its purpose? Nope. Design is very much cyclical, if you study the channel's history. I'm sure a rebrand will come within the next few years, but I'd expect it to be an evolution of the current brand, not a full revolution, like 2013 was. Visual tastes differ from person to person, but, you have to give them credit for making an honest effort to unify their visual identity for the first time since 2008, and arguably since 2003.
Reference video: check out the hot mess that was on-air graphics in August of 2013 at 0:10
http://youtu.be/j9X3rP_HXRQ
Couldn't have said it better myself.
What also impresses me is that they've been continuing to maintain their graphics and format without sprinkling in some new openers/graphics along the way, something they've failed to do during all their previous campaigns since the Bringing Weather to Life era started.