The concept of a fallen 'angel' (So to speak) as a consequence of her actions (Using her healing abilities to harm)
Excerpt from Soraka's current lore:
Soraka realized that she would have to fight to save her friend. The stars screamed in her mind, telling her not to use her powers for harm. Ignoring their warning, she struck the attackers with a flash of brilliant light. Crying out in terror and shielding their eyes from her divine radiance, they fled. Soraka's celestial form faded and the stars fell silent - for her transgression, she became mortal.
She used her abilities to harm and for her transgression became mortal. I know the circumstances are kinda different (Old lore had Soraka cursing Warwick, where as here she used her abilities to bring harm to Warwick's attackers), but I don't see how this is so much worse of a change to be, as you put it:
the complete garbo we have now.