Isn't Backbone.js already 6.5kb, Packed and gzipped? Why is the stress put on making it smaller/modular? I don't think that is the problem at all. The problem is one that frameworks like Ember.js are trying to solve... reuseable, convention-based and opinionated. This is what Rails got right and something I think that client-side frameworks lack. Rails' success, for the most part, is due to its really strong opinions and conventions. These client-side "frameworks" are often brought in with the byline that its intent is to be TINY. To me, that's not what these ambitious JS frameworks should be bullet-pointing first.