MVC may not be a solid pattern for a client side framework. It makes sense to contain some semblance of state with in the presentation layer on the client side, rather than working with a stateless MVC pattern.

http://www.martinfowler.com/eaaDev/uiArchs.html MVP via M. Fowler seems a little closer to what client side should feel like (imho).

http://en.wikipedia.org/wiki/Model_View_ViewModel MVVM also makes sense for a client side app, which is just an extension of MVP.

IMO MVC on the client side is just a carry over from people who were experienced in writing web apps who wanted something that felt familiar on the client side. It's a leaky abstraction at best.