I'm glad Nintendo built a microphone into the gamepad so it can never be used.

Playing against folks on Mario Kart 8, though, they aren't that stupid. Most of them are only mediocre at worst. I've seen a few folks get way behind on tracks, but i think we've all been there once or twice :/

Voice should be defaulted to OFF so kids and parents that have no clue are safe from creeps from the start, if someone wants voice they have to actively turn it ON through a parental block/password, this should give everyone what they want, and cover Nintendo's ass

Parental controls. Leave voice chat off by default so people don't assume you can hear them. Have it so you can easily report bad behaviour in game.

This is Nintendo. If they could afford to properly moderate it, and Nintendo gamers develop the right culture to readily report abuse. And make it an offence to spam annoying non-game related stuff in chat. They could actually be the company that shows how voice chat should be done.