In short, any attempt to use cremation as an expression of a disbelieve or even denial of the resurrection of the body is discouraged. That includes scattering the remains, or any other gestures of disrespect to the deceased or to God.
Historically, cremation was promoted often with such atheistic overtones, so the Church at the time was more strongly opposed to cremation than she is now, when cremation is typically chosen for economic reasons.
If I choose to be “sprinkled”, that is not a sign of disrespect to God. I’m pretty sure God won’t need my ashes to resurrect me. He is all-powerful, after all. My sprinkles will be in places that I want my grandchildren to visit and remember me. Reading, studying, fishing...all good reasons to visit Mimi!