Why is Ultra Rapid Fire not in the party game rotation?

It seems that everything but URF is being cycled through the party game rotation every weekend? If anything, it only seems happens on a blue moon.

I'm sure a huge percentage of the League community enjoys playing URF mode a lot, and it seems to be a great way to test the full potential of champions within and outside of their comfort zone. It might even introduce us to a new champion they haven't played before.

Also the high paced action is taken to the extreme with URF mode. It's essentially an adrenaline junkie's dream. 80% cooldown reduction, no mana costs, tons of builds to make (even ones that might not work in normal/draft pick), the list can go on. There's nothing more than being able to use a champion to its highest potential playing URF mode.

I've been hoping for the game mode to arrive since April 22nd after L4T3NCY announced it in this game updates post (http://oce.leagueoflegends.com/en/news/game-updates/gameplay/rotating-game-mode-queue-now-live ), but it didn't show up and has never shown up since. Why not bring it back?