I guess os x is simply trying to integrate disc burner more--you know, so the user doesn't think of it as a separate app but rather an inherent part of the os.
toast titanium is definitely worth the $$. I don't have it, but every day I wish I did. disc burner has this 'copy before copying before burning' thing which is annoying. toast burns right away. and burning is easier, I believe, with its interface. it also works with itunes--drag and drop a playlist from itunes window into toast's audio cd window, and it loads the songs, just ready for you to burn.
it's a quality app in my opinion.