Dark mode serves a purpose now more than ever (besides user eyesight) with the release of OLED panels into the business market. As those become more common, it will be a necessity for software to adapt because users don't want UI elements retained in their screen panels.
With that said, it is possible this could be something the community could handle if we felt like it as a lot of the UI is stored in plaintext .css or .xml files with .png for the icons, this allows editing it. See screenshot for example (I only edited the button color), but it'd require painstakingly mapping each file to the appropriate parameter/UI elements .. unless you did a Replace All on specific color codes pulled from the UI. The files are located in: C:\Users\<USERNAME>\AppData\Local\Autodesk\webdeploy\production\<VERSION HASH/UUID>\Fusion\UI\FusionUI
It's one of the reasons why Windows has been making a push on it as well at the OS level.