Is there any reason why we can't have custom hexakill games?

I personally really enjoyed hexakill when it was around. Having double mid/top or double junglers was interesting to say the least. I feel like having this available as a custom game would be really nice and wouldn't really require much extra work from Riot. It's basically just like normals except with one extra person, right? We could have this available on all the maps 24/7 with zero problems, right?