I made one character a few weeks ago and I've not made it out of the city yet. The city itself is pretty amazing. I was honestly impressed with it. There's a lot there compared to ESD. But of course the Federation also has Memory Alpha, DS9, other outposts, etc. I know the Klingon faction is incomplete.
As for why that is (after two years), I wouldn't even want to guess. But if you're implying it's because only about 10% of people play that faction (thus not as profitable?) then I wouldn't disagree, though it's just another example of short-term gain vs. long-term sustainability, because having a full second faction is actually in the best interests of this game.