All of the players that made the game worth playing (for me) have left, because the game is stagnant and the majority of staff (including management) don't care about the game and take the size and success of it for granted.
With the lack of gameplay-oriented development, it's been dumbed down to an interactive chat room where you pay absurd amounts of money to dress up your character. Things like Discord exist now though, and if people really want to chat with people then there are better solutions than logging on Graal. You aren't offered much else when you log on anymore, because it's not much of a game. There isn't much gameplay past a certain point.
Yes, to some degree the invasion of Brazilians has hurt the community aspect of the game. They can't speak the language that the game is advertised in and their ping is ridiculous on a game hosted in the US. Other than that, it's the community eating itself alive: I log on and find myself at the spar arena, which used to be somewhere I could spend hours a day and sometimes winning 300+ spars in a sitting, to now be surrounded by weirdos and alternate accounts who constantly just flame and harass people all day long. So, in that regard, even the social aspect of the game is pretty awful now.
More than anything though, it's probably just people getting older and realizing they can't enjoy the game for natural reasons anymore.