A medicine for despair
Why teach Buddha-nature?
If awakening is imagined as something imported from outside, practice can become self-rejection. Buddha-nature teachings reverse the orientation: delusion obscures or misrecognizes what is already possible, but does not create an essentially defective being.
The language is therapeutic. It encourages practice because transformation accords with reality. It does not promise that every impulse is wise or that training and ethical repair are unnecessary.