> LoL doesn't have voice chat. Okay.
> Splatoon doesn't have voice chat, it's a sin by Nintendo (at least to ign).
It's a very straightforward game where you are doing your best to cover the ground and walls with your color paint. You see an enemy, you splat them with your paint. Blank floor, cover it! Enemy paint, paint over it! It's such a fast pace battle that there really isn't even time to talk much during it. The most I could make were laughs, grunts, and "oh come on!" when I got splattered.
Having to have people shout things out at me while I'm already trying to work the motion controls AND move both joysticks AND dodge the enemy attacks AND maneuver in squid form to make sure I have enough Paint AND check the map to see how far we are ahead/behind is going to be more bothersome than worthwhile (and don't say just learn how to multi-task, because I have no trouble with that, but it's definitely annoying when people are pointing out and trying to tell you things when you're already focused on one thing). I mean, sure there are kids that will whine and complain and shout at you like with other voice chats, but I'm more annoyed at the thought of dealing with arguing with teammates over a 3-5 minute battle where there's not much coordination needed. It's not like a misfire kills you, or how dare they save you by taking out the enemy that you were going to take out or share the same ink that doesn't disappear if they use it to refill their ammo.
Basically as everyone else said, it's not needed. I mean, sure if it was just for free matches and they were friends that were organized and worked together well it would be beneficial, but I highly doubt that is what the vast majority of people would use it for. Heck, even if they made it an option, I doubt that many would have it on since they would probably be tired of it feel fast.