The problem came from the new client.
Each game mode had to be implemented individually. LotPK and Ascension were the first game modes to get implemented, making them high availability in the first couple of months.
And while riot is still working on implementing the older game modes, they are not letting that get in the way of making new ones. (Blood moon, Dark Star, ARURF) So their work is kinda split.
I'm still kinda itching for them to implement TT Hexakill, and Definitely not Dominion. Though it's hard for me to say what my favorite is.