Why are the core JS/CSS files handled separately in CClientScript?
It would be great to have the dependency feature, for example, in our own modules and applications.
Any plans to refactor this class, and normalize the way that JS/CSS files are handled, so these "core only" features can be made general purpose?
In my opinion, there’s no feature in a framework that’s too internal to be useful to a developer - I say, expose it all! And let the developers make decisions about what to use or not.
Essentially, features that are designed for internal use exclusively by the framework are not generally useful - you eventually end up with (work and runtime) overhead in applications, as a result of developers trying to emulate, hack or reinvent features that were not exposed.
I’m a pushy f*ck, I know 
But a framework is a software developer’s toolkit - and as such, every component contained should be designed for use by the software developer. If you find yourself writing code that only serves the framework, you’re not doing your best.
This is not a criticism of Yii - but it’s only the best PHP framework ever written, that doesn’t mean there’s no room for improvements