Quote Originally Posted by Ghastly View Post
It's about time they let me summon Byakko or Tsukuyomi
These are two great examples for why they probably won't do that - Tsukuyomi - and Shiva - were only summoned into host bodies, we don't know if they can be summoned on their own, same goes for Susano. Now, Susano at least was said to be a Primal, but Byakko isn't. There's no lore reason for us to be able to summon him. And it's this nitpicking - you can summon this but can't summon that for some arbitrary reason - why they're not going to give us more.