It would be cool if when you played ranked there was a voice chat that you could join. If a player joined the voice chat, it would say someone joined it and you could decide if you wanted to join it as well.
I just wish it existed. Would really counter the duo Q bull crap in high elo ranked. It's literally "Who get's the duo Q" and "if the duo q is decent, u lose".
In high elo, telling your laner/jungler a crucial piece of intel/information or to behave a certain way to bait something can win the game. Even in low elo, if they have a fed tryn, you could say when to stun him, to back off. You can't type/ping that exact information you want to convey.
Dota 2 has it. In dota 2, people rarely said anything bad in my experience. That's one thing I enjoyed.
Also, can easily just make it honor level 1 2 or 3 to use. So people who get banned/chat restricted can't use it. Maybe they can listen though still?