While I personally love dark themes both on my Windows 10 PC and Xbox One, based on the feedback, Microsoft is now offering a scheduled theme which will automatically switch between Dark and Light theme based on Sunset & Sunrise. This is a new feature along with variable refresh rate, twitter integration, and 1440P support for TVs.
Automatically change Themes based on Sunrise & Sunset on Xbox One
Navigate to complete right-end and open settings.
Navigate to Personalization tab, and select Theme & Motion.
You should see a System Theme drop-down.
Select Scheduled from it, and then choose Sunrise & Sunset.
That said, here are my two cents. The switching option works well when your Xbox One is placed in a Living Room which has ample of light from outside. So as it gets darker outside, the theme can switch to dark. This makes sure it doesn’t hurt your eyes and stays light when there is sufficient light from outside.
Most of the gamers have Xbox One either in their room or a closed environment where themes don’t matter, and if you are playing in dark, you will always need a dark theme. In this case, there is no point in using the themes option.
In addition to all these new features on Xbox One, a subset of users may also see additional experimental features that Microsoft didn’t mention here
These features are only enabled for a portion of the Xbox audience to gauge interest and collect feedback.