Now that the Shougi game got released, that was I believe the oldest Japanese game, which had gotten released in MAY.
And importing games is expensive. Typically Japanese games go from $30-$50, plus shipping (which can be spendy by itself). I'm sure that's a lot of the reason why most US dumping groups don't go after the Japanese games in WRG's absence.
The problem now really is not the lack of groups, but the lack of large groups. There's a ton of these little groups popping up left and right (especially in the US market) but if their funding is as big as their group, they can't do much.
While it may be possible for them to cover everything, if a few of them consolidated, they might have the financial support then to go after a huge number of releases.
But that's just my thoughts.