Depending on your perspective, it's either a smart move or extremely unfortunate that Sony is reducing the amount of proprietary software it puts on its phones. But whether you love Sony's mobile skin or you're more of a stock Android fan, the stripping down continues with the loss of Xperia Themes on the Xperia XZ3 devices due to "low usage."
In a support page on its website, Sony stated that while the theme function is gone on the XZ3, users can still download and choose wallpapers from the Google Play Store. Plus, XZ3 owners can continue to use the live wallpapers from a particular theme, though they won't necessarily support all of the animations and local assets the theme offers.
Intriguingly, Sony notes that devices that are upgraded to Android 9 Pie will still have themes. The Xz3 comes with Pie out of the box, so this could be a reference to other devices. In any case, the loss of Xperia Themes on the XZ3 is no doubt a sign of things to come. After all, the Xz3 is Sony's top-of-the-line flagship, so any forthcoming smartphones from the brand will likely follow suit.
- Xperia Blog