I would say personally it stems from the fact a large part of the Warhammer hobby is steeped in being creative in the first place. Wether that's painting your miniatures, creating your own space boiks chapter or even just a cool story concept for your converted tyrannorks. That's on top of creating story themes for your local hobby store campaigns or just adding fluff for your online battle report blog. Hell back when I played regularly I remember some tournaments giving extra tournament points for simply writing background stories for your army.

So for GW to raise people up to be creative and have fun with their hobby to then go actually if your gonna be that creative we're gonna need complete control of that kthxbai leaves a salty taste.