Part of the problem is there's no other freelancer servers run by MS anymore to help support interest in the game to jump on. In fact, about the only server worth jumping on now to play the game "online" is yours. All other servers running the same DISCO mod have less than 10 players on them for the most part, many are even worse for numbers online. As you say also, it's a very old game and not many places sell it now, most get the game via Torrent download. And those who might be interested in FreeLancer, played it to death many years back when new and MS servers was around.
As for this server itself. Thing is, once you've earned enough to fly and test the best CAP ships e.t.c, you kind of lose interest in it after that. There's not much left to trade for earning credits to buy, only the RP side of things remains to keep you interested then. Sadly, same with all games, once you've done what you wanted to do and get, you just lose interest.
I've had numerous breaks from FreeLancer over the years, some lasting years before playing it again. A lot of the new players you'll get, are not new players to the game as such like myself. They come along and test a new mod for a while, after not playing freelancer for a long time. But it's only a matter of time before they get bored and take another break.