When the Gra made a חרם he was not inventing a halachic category but using one that already existed. The reason he wrote elsewhere. The Gra held the teachings of hasidim are from the Sitra Achra and that its energies are fallen energies--miracles given to them like the miracles done by the Golden Calf. Miracles and powers of the Dark Side.
So why is it ignored. The institutions that would normally be following the Gra were infiltrated and taken over. That is Lithuanian yeshivas. [And this also explains what many people wonder about --why are Lithuanian yeshivas corrupt? Well now you know.]
The answer to all of this is simple. To start paying attention to what the Gra said. It could not be more simple.
The only way now is to be for or against. There is no middle road. I though before I could find one but I see now that was a failing strategy.