She is not even a forsaken but rather lightforged undead. She suffers none of the downsides of being undead and seems to be a special snowflake that was invented as anti thesis to what Forsaken actually are.
She is technically an alliance character with zero connections to the other horde leaders. Like she is literally on BFF status with both Anduin and Jaina.
The Forsaken are all about melancholy and shadows. Calia is fully absorbed with the holy light.
Being a Forsaken means you are rejected and cast out. Nobody rejected Calia. Infact she was welcomed with open arms by her friends in the alliance.
Lilian Voss is in my opinion a much more fitting candidate for leadership and I hope Blizzard will not just hamfist her onto the forsaken without any ingame connections for Forsaken players on her side.
Leave your 2 cents if you want to.