I don't think that Dreamweaver specifies external style sheets in a set of pages (site) by default. Even if you reuse the same styles over and over again in multiple pages of the same site, it doesn't know how to create a CSS file. I don't know if you can manually do this via a certain option in its vast, lengthy menus but inline styles aren't exactly the best thing if you reuse styles, in fact CSS was designed to ease designing by applying certain properties to a whole bunch of tags, not just one at a time using style="".

Oh yea, I was moreso just commenting on how a lot of people think dreamweaver makes it faster to develope multiple pages since you can just copy/paste and quickly tweak the differences rather then having to copy code and modify it accordingly. CSS pretty much manages this like you said