It looks like dust on a screen. What's a purpose of this improvement? Random noise in animation can be minimized with plugins but static noise seems to be hard to remove.
If you render animations with enough passes/quality to get quite clean image, then static noise is better as it makes image look a lot cleaner. That only applies to images clean enough they do not need denoising. In that case, if you have animated noise pattern, then you still see grain, even on very clean renders. Also, imagine you have an animated shot with static camera and very detailed geometry with strong highlights. Like grass for example. Animated noise patter would either ruin that shot, or make it render a lot longer than it needs to
So it's simply a preference, and both options have their important place. There will be toggle to switch between static and animated noise pattern in 1.0 version. It won't be buried in debug settings anymore. It will be a simple checkbox right in the common UI.
