Rotating Game modes

I have been played league for a while now, and I am very disappointed with the lack of frequency for rotating game modes. I find it very baffling that riot can go a month without having a single rotating game mode at all. Does anyone know the reason for this? Even a poro-king or domination is more fun for me then summoners rift over and over. Hopefully they will allow us to play all game modes or more then 1 at a time, I want star guardians back and howling abyss- draft mode and such.