@Lawrence: I wasn't really meaning 'bulky' in regard to the output of it , javascript etc, I was thinking of the bulkiness of having that as part of Dreamweaver itself.

A lot of people wouldn't want that feature in the app or use it. I would guess that it would also increase the development effort required as Adobe would have to maintain Dreamweaver and Edge with similar features. Much better to have Adobe focus on Edge as the app that does that than to include the same feature in DW. I can think of a lot of other improvements I'd rather see in DW over and above Edge-like features.