It would be nice to have consistent coloring on the phone.
It’s important to note that unless this changed, not even the dynamic coloring is truly “Material You”. The whole point of Material You - and why IMO it’s such a disgrace to UI design - was to severly weaken and largely remove the rules of Material Design, in turn allowing everyone to do whatever they want with the UI within a few boundaries, creating a somewhat consistent but highly customizable experience.
Which would solve the one big problem companies had with Material Design: It was difficult to not look like another similar looking app in a sea of similar looking apps.
Funnily enough, although I suppose it’s a good thing, everyone just uses the standard setup for virtually all parts of their apps, and that includes the dynamic coloring and all that. So we got a consistent look, but more because companies are lazy. 😅