I believe some people would like to change those theme with a single click or I saw one request to set theme to change as changing from morning to night theme. etc.
That's correct. I want to change my theme with Task Scheduler to a dark theme at night and to a bright theme in the morning.
The reason for the command line is that you can trigger it from anywhere. 
If implemented then I can switch back to using Curtains again by replacing the program "Auto Dark Mode":
- Auto Dark Mode (can change theme automatically, at specified times) (Github page)
- DisplayFusion (has command line support)
