Well, heres my theory...
When Freespace 1 and 2 came out, the majority of people that bought these were young, you know...maybe 10-20 range. Now that we've gone five years in, the younger players are getting older, thus having more advanced things todo to complicate their past ways of computer-RL balance. This usually means having to adujust to it by cutting the gaming/online factor down.
I am currently thirteen years of age, I have about another perhaps 2-4 years before real life really starts to interfere with my being online. This is basically a way of life...usually people around 16-26 are really busy at some point, may it be school, college, going for their first job, going out on their own, etc.
It really isnt because of the game itself in most factors, its the age group that is entering an important time.