The artsy waterfront areas that are now gentrified were originally large dilapidated work lofts that were not really intended for residents. Many of them lacked bathrooms or kitchens. There is a really good new york times article from the late 1980s that talks about how residents coped with the lack of such basic amenities (I can't find it now but I used it previously in an essay).

Rezoning paved the way for true residential housing and with that came the high prices.

http://en.wikipedia.org/wiki/Williamsburg,_Brooklyn#Gentrifi...