Why Nintendo don't just make a direct talking about online to explain everything? All of this is becoming more and more confusing and killing my interest for the console.
They likely will be. They haven't talked about the OS and UI in general yet. They did before the Wii U launched so it's likely coming. This Splatoon info isn't actually any different from what we've heard before but we ultimately need to see what Nintendo has planned in action.
Worse cast scenario is this.
You play online with no voice chat. Which is what you experienced on the Wii U. What you likely experience on the PS4, XBO, and PC when you don't bother to hock up a headset or go into the options and turn off voice chat. Let's be very honest here. A LOT, LOT of people do just that. The vast majority of people don't bother with voice chat even when there is an option. If you use discord or something similar you'll continue to use that and go about your day.
The app is apart of the overall package and will do a lot more then just voice chat. You can likely just ignore the voice chat feature like so many do on other systems. You aren't paying for the app. You're paying for the access to online play.
Best case scenario.
The App is actually easy to use and somehow makes things better without to much trouble. Maybe some of it's features are integrated into the system OS itself. People still put people on mute and the vast majority still don't bother with the voice chat feature.
The voice chat isn't the biggest issue here and never was. What the online service is like in terms of server stability, speed, discounts, downloadable games, price, etc are all far more important and bigger unknowns. That people zero in on this, feel so angry, when it's such a small aspect and an aspect people generally ignore has been really confusing.