Just a note, that 20kb also includes the dependencies, such as the reflect metadata polyfill, zone.js polyfill, and an ES6 shim such as core.js. Once static template compilation lands (think of it like the JSX compiler), it will get even smaller.
Angular 2 is shaping up to be a framework like no other out there in its capabilities.
20kb? Really? On last week I built NG2 application(rc.4) with one component and size was over 500kb, with all dependencies which needed to run it. Maybe @angular/core weight 20kb, but in order to run real world application need add many dependencies. rxjs, zoom.js, shims, and so on..
We have 75-100 components along with all the angular pieces, polyfills, and ngrx/rxjs. It's 250kb with a minimal build process. I haven't even started digging into any optimization/build tools. I think you're doing something wrong.
I heard they are going to reduce final app size by doing smart analyzing of used features and getting not used stuff out of the final build. But I might be wrong.
Angular 2 is shaping up to be a framework like no other out there in its capabilities.