>>538010013
A combination of things.
One WHF had had a pretty long sales slump because they had refused to put out a new edition for years.
Certain aspects of the long delayed then cancelled 9th edition were folded into End Times.
Two they wanted something that was more copyright friendly, "Urruks" instead of "Orcs".
Three they were still pissy about Storm of Chaos not going their way.
GW is a very weird company, I was surprised to learn they have been publicly traded since the 90s because they are so petty and bitter about everything.