Why can't we have the option to switch between HUDs? Both are currently active.

I'm not saying the new HUD is bad, and I'm not saying the old HUD is good. However, many people have reasonably asked for the option to switch between HUDs. Riot has said it is due to technical issues with supporting two different HUDs, but how is this a problem if it currently exists? I can onto Butcher's Bridge and use the new HUD, but if I play ranked solo que, at the moment I still have the old HUD.