connected to this: a lot of content in pages is often pulled in via js.
For example, facebook's page as seen via links is basically a long list of script tags without any content.
Without javascript evaluation it seems that a lot of content would be lost.
Based on my usage of Firebug I am under the impression that even if stuff was put onto the page with js (or if the html source is badly broken), the browser will build a valid DOM structure of the page and should be able to save it out as html/css.
Without javascript evaluation it seems that a lot of content would be lost.