Another few advantages are centralized presentation definitions -- make a change in one place to update the entire site. importing CSS to the html source seems very very silly to me.
I'm not sure I'm interpretting you correctly, but if you're trying to put styling back into the HTML tags, you're not going to be able to keep the browser-specific stuff.
Can you give us more information about what your end goal is? There's always more than one way to do it.