Well I started playing when I was 10, and now I'm 18, but I think the age difference has nothing to do with it. When I first started I played it for hours on end, sometimes spending entire days on it. But overtime a lot of the people I would play with stopped playing, and on top of that a lot of the things I enjoyed started going away (types of servers, etc.).
The loss of maps really didn't help either, I still played after the update, but the maps were such an important part of the BL experience to me that I felt like something was missing.
And life.