The whole point of the game was the map. No other game has a map that allows real time knowledge of almost all of the opponents movements and actions. In fact, I used the map to paint while looking for other spots to head to, it's that's accurate. This also allows your team to always know where to go with out you saying a word. As soon as you're splatted, everyone knows where it happened and which way the killer is going. This also affects the accessibility of the game, allowing for a whole new generation of shooter fans to rise out of a fan base that critics assumed needed Mario slapped all over it to be that successful.
In spla2n, that is all regulated to a couple button presses. This seems like nothing to us, but to that first group, that learned to play by tapping the screen to help someone or get to a teammate, this is a skill check/gap. Instead of looking down and using the real time map at any time, they now have to choose when to use it. This is a big thing as games are super short, so every moment that you're hiding in ink, is a moment lost. On top of this, now, you can't just just tap and go, you have to hold and select and then go, which means waiting to see if they're going to die and you're not just about to drop and die yourself, or maybe they die and now you're​ either switching to someone else, which means actually switching to them, making sure it's safe, then jumping. So most aren't going to do that, they're only going to check when they die, and if they're "good" they may not check it at all. Which means for awhile the prevailing meta will be played like CoD where people just rush from kill to kill instead of actually looking for and battling over spots, which will affect the map and game flow overall.
It's just a completely different game, which is what makes the port talk hurt all the more. They could call it Splatoon and call it a reboot for the switch and I wouldn't​ disagree. It's like JSR to JSRF, same series, different games completely because of the loss of the base mechanic.