It's hard to believe, but when I registered here I was just shy of 14. I'm almost 28. I'm user #306. These forums were very different back in 2004, and attracted a lot of cool people. Those very people have moved on with their lives (as have I).
Forums boomed from 2002 through 2008 because there simple wasn't an alternative. 2009 marked a turning point for many technologies. The financial panic created a "shake out" not just on the Internet, but in the physical world. People looked at budgets and looked at alternative tools.
Communities utilizing forum software will always be around,