WSA wasn't intended for calls or messaging. It was intended to allow developers who had developed apps for the Fire tablets to also provide or sell the apps on Windows.
It was also an alternative way for Android developers to write and test code on Windows. You could edit/deploy faster to WSA than to an Android emulator. And WSA apps are resizable, which is handy for seeing how well your code could handle different Android layouts.
The drawback was that WSA did not have any Google Play services. So no map, no Android push notifications, etc. That could have been addressed if Google wanted to license all of the Play bits.
It was also an alternative way for Android developers to write and test code on Windows. You could edit/deploy faster to WSA than to an Android emulator. And WSA apps are resizable, which is handy for seeing how well your code could handle different Android layouts.
The drawback was that WSA did not have any Google Play services. So no map, no Android push notifications, etc. That could have been addressed if Google wanted to license all of the Play bits.