True about painting the map but that can be said about various game modes in most shooters. You could just go around standing in 'zones' for similar 'hold the territory' type matches in other games for example, or run and hide with the 'oddball'. Whilst you're not necessarily killing anybody, you're still helping. I think all shooters have their own variation of these types of matches, the communities just focus more on the Team Deathmatch gamemodes more.
Splatoon focusing more on these 'objective' type game modes though is nice, especially since I prefer having a real objective rather than 'shoot more dudes'. I get sick of Team Deathmatches. If you try other objective game modes in other games, all the players are just going for kills rather than the objective anyway...
The precision and concentration in CoD maybe, since headshots give more points and a guaranteed kill. However, you can also 'spray and pray' with any fully automatic in the general vicinity of an enemy and get the same results since only 2 or 3 of those 50 bullets actually need to hit. Obviously the 'precision' will make a difference with snipers and other generally slower firing weapons (which obviously does show more skill) but overall, the skill level to do reasonably well with online multiplayer is pretty low thanks to the viability of 'spray and pray'.
When you look at really good players though just raking in kills non-stop, they're reacting to seeing other players before even you the viewer notice them. Those 'twitch reflexes' are a lot more important to those games.
Compared to something with larger health/shield bars though like Halo, precision can make a much bigger difference. Headshots make much more of a difference since they can drain an entire shield in a few shots compared to the usual 'entire clip' with hits to the rest of the body.
Plus these games are often 'faster paced', for lack of a better term, with people jumping around and (in the case of Doom or Quake) moving at stupidly high speeds. It's much harder to hit a guy in the head when they're running and jumping around like that, which is often absent with other shooters.
So if you see somebody first and shoot them in the head they have time to actually react to it, so if they're a good player they will probably out-maneuver you and take you down with a few well placed headshots as you flail around spraying bullets at the wall screaming "HACKER!!! OMG!!! I BONED YOUR MOM!!!"
They both require some sort of skill, just that Splatoon is more comparable to the Halo/Quake variety than the more modern CoD style.
But this is pretty irrelevant to the thread. I was just curious to what you originally meant to it requiring less skill, which I kind of do agree with to a degree since it's more about painting stuff than getting a high K/D ratio :3