Yes, we definitely need module-specific .CSS files ... in fact the existing CSS I'm talking about is acs-subsite specific and  contains classes and ids (both are used currently) for elements that appear throughout a subsite.  navbars.  template list builder elements.  portlets (boxes).  stuff like that.

And we do have module-specific .CSS in some cases, for instance calendar.

So incrementally we're moving in a direction not much different than you're talking about, absent page-level CSS (do we need a standard way of specifying that?  it would seem to work against thematic unity within a package if one goes hog-wild) and the "overriding" notion.

I don't think there's any disagreement about continuing to push in the CSS direction ... just questions about who will do the work and when.  Including design of the structure, i.e. classes and ids.

Since Lars and Jeff have done more thinking/working on this than anyone else I'm aware of to date they definitely need to be part of any discussion on this topic.