There is this older thread addressing this:
And I’m aware that color and alignement exclusions are coming in the next version. (It’s really nice and will make this problem really less annoying)
But, overrides are there for a reason. Consistency seems to be the reason mentioned, but overrides are meant to break consistency.
What is the point of overrides if updating a style clears them?
In other design software, in my experience, properties that are overridden stay overridden even if you touch the original style.
If I have decided that this instance of the Textstyle is in Uppercase for some reason, changing the style from size 12 to size 14 should not affect my Uppercase override.
Only properties that have no overrides should be updated on the instance.
Just my opinion.