Gamemodes In Custom Games

I'm not sure if i'm the only one that feels this way, but why can't we play all game modes in custom all the time? I can understand the rotating game modes, as if they were playable for matchmaking all the time people would possibly stray from ranked, but I feel that there is no harm in letting players play any game mode in a custom. I think it would be awesome to be able to play a custom URF game with a few of my friends, or a one for all, but sadly that isn't an option. Is there any way that this could be available in the future? Because i'm sure there is a lot of people besides me that would welcome the change as well.