Idk, I think I was going to end up using a third party like skype/raidcall/etc. anyway b/c the microphones on the gamepads are pretty bad.
I posted the video just to show everyone that there are people who still want it.
I think voice chat will be very important, for building team strategies. Do I think it will be useful moment by moment like CoD? No, because Splatoon is indeed fast and you are constantly dieing and respawning anyway. However perhaps halfway through the match when an adaption needs to be made, or most importantly at the end of the match when you're team is deciding what weapons everyone should go as. Then everyone could decide what role they will play (backup, attacker, infiltrating enemy base, etc.). In those regards it will be crucial to talk to your Squad, as you talk to each other, decide what strategies work, it will only help Squads find their go to strategy and get better quicker.
Again, most likely the the squad I'm in (Inkzooka Squad) will be using 3rd party anyways. And besides I'd rather nintendo use their time improving the game in other aspects (if it required no effort on Nintendo's part, then sure why not)