In my opinion, it's because Discovery GC is no longer the same beast that drew veteran RPers in years ago.
When I first joined Disco, I was not accustomed to roleplaying in freelancer. I had played on the RAW server, which was a vanilla pvp server. There was some unenforced RP there, but only a few players actually put any effort into the RP - when I met them I had a blast, but that was not the focus of the game for me.
After microsoft shut down support for freelancer's global server, I had to go online to find mods or communities with private servers that I could continue playing on. Discovery is the one I eventually stuck with, for a few basic reasons:
1. The RP here was fun. Simple as that - there were fewer rules back then, everyone RP'd because they -wanted- to, and it was easy to find others to roleplay with.
2. The ships. Most mods were vanilla ships only, or had mixed genres (like the mods that add ships from starwars, bsg, star trek, etc.). Disco gave access to the capital ships and larger transports that made the single player freelancer seem so epic.
3. Population - Disco was big back then.
Over time, discovery has gone through a few distinct phases:
-At first, the trend was to add new ships, new factions, and new weapons, and in general to do things to improve the game-side aspect of the community, which made players spend more time in-game rather than on the forums and created more face to face RP.
-Then disco received an influx of people who didnt follow the simple rules that the community set forth. Because of this, discovery's admins had to become increasingly more strict, and the rules for the community changed from a handful of common-sense restrictions to a plethora of if-this-then-that strictures that sucked the fun out of the game. No longer were players free to create RP that both they and the other gamers mutually enjoyed, now everyone was restricted to doing what everyone else thought they should do. Creativity bombed, and most in-game RP was forsaken for forum RP to avoid sanctions.
-The result was a decline in the population of good roleplayers in-game, which lead to an increase in the poor roleplayers, poor english speakers, and pvp-oriented individuals now that the server's limited slots (which had previously been occupied by those roleplayers) were being freed up.
I like a good story, and that used to be something you could find in-game, but now every single word that people type out in the game runs the risk of insulting someone or being a sanctionable offense. When the game is no longer a good place for your story, you take it elsewhere (which ended up being to the forums in this case, and eventually to other games as those players got bored with freelancer's environment).
Long story short: too many factions, too many conflicting points of interest, and too many rules.