The reason is simple somewhere in the upper levels of the game or company the decision was made to use Discord as the primary method of communication for Elvenar. That was all, and yes it was announced that the forums would remain for the time being. The uproar this caused may have forestalled any "shutdown" of the forums and as of this week, no plans have been announced that this has been changed.
As Discord is the "new" communications channel all information from the game itself is directed there. However, INNO does still support the forums, else they would not exist at all. It might not be to the level we would want but that fact is true.
This was done, again from the game or company side to provide direction to the "primary" communication channel.
While we agree, this as far as the US team was concerned was not our decision to make, as I stated it was made from above and passed down to "ALL" of Elvenar worldwide