I'm not sure whether it's growing, but certainly the cost of housing, and the frustration and frenetic pace of modern American living make living aboard a seemingly attractive choice. The good news / bad news of course is that it isn't attracting sailors so much as it is those seeking relief or a change. I'm actually at the point where I am glad that restrictions on the percentages of liveaboards permitted in a marina are being imposed. It's discomfitting to think that my moorage/slip rates and availability might be restricted just to provide for more housing rather than to use my boat sailing.
I think the realities of boat living (whether on a $60,000 ex-cruiser or a $500k new catamaran) effectively thin the herd. With no boating background, the novelty wears off after a year or two. As for New England, or my home grounds in the PNW, year round living aboard is only for the hardy ones or those with no dollars to do anything else. The PNW being the more survivable locale between the two.
I noticed that many boats in Rockland/Rockport this year still didn't leave their moorings despite an awesome weather window over the 4th of July holiday. Moorages and marinas reflect this reality that even amongst those who own boats, few actually use them very much. They represent a dream more than anything. In today's environment the luxury of spending on a dream is fast fleeting...