I'm a little confused. Didn't ExtJS, Dojo, various jQuery plugins, etc do this same kind of thing years ago? And didn't we kind of find out that JS + CSS + HTML was acually a pretty nice separation of markup, formatting and functionality?
That said almost every example on the site is just creating HTML and JS (not CSS), so it would be very easy for you to use OJ to create everything and then style everything with .css files like you always have. So use it however you want, but please don't think it is trying to force markup and formatting together!