You know, I could definitely live with it if Geedubs purged the Grey Knights. The Ultras have some real fans out there, but I strongly suspect that Matt Ward is the only person who was ever super into the GKs. I don't even remember what they were like before he fucked their lore up, I'm not even certain they existed before the Ward Era.
Before ward era they were like living maguffins, like if the Men in Black were walking battle tanks. I think the thing about them was that they were the most mysterious militant branch of one of the strangest branches of the secretive inquistion, they did not feel like space marines, feeling more like terrifying executioners. On the tabletop due to a lack of updates they were not competitive at all, requiring expert control to not horribly fail, which I think is appropriate for inquisition resources. You had to essentially have a stormtrooper backbone with chimeras galore, with the actual Grey Knights serving as a surgeon's scalpal to eliminating high value targets before escaping from tarpits and allowing stormtroopers to clean up the rest (as the poor guys often have to do) or bring in orbital bombardment.
In the new edition fluffwise they were... Ok, ignore Ward fluff. New BL fluff sounds pretty awesome, I haven't read it myself but reading the synopsis it sounds more like they portray the GK less as men in black and more as SCP + inquisition, dealing with the vastness of chaos because nobody else can
On the tabletop, they suffered an initial backlash due to immense cheese, baby carriers and Matt, but now they are less "storm troopers doing all the work whilst the surgeons do god knows what" and more "MIND BULLETS, I USE MIND BULLETS AHAHAHAHA MAGIC MISSILE MAGIC MISSILE MAGIC MISSILE" with the addendum that you may still need to bring along stormtroopers (getting no breaks), but the GK can definitely hold their own as a standalone, where they effectively function as a small, localized exterminatus - fittingly, focused on killing very big things, demonic things, big demonic things, and more or less ok at killing small single wound heretics (though large massive groups of small normal things will eventually overwhelm them, so leave that crap to stormtroopers).