I am playing Games and Shooter over 20 Years and Splatoon is the only spark of light i saw since well... Call of Duty 1 and Unreal Tournament 2003?
Anyway, i CAN see your point dear OP but there are two miss conceptions in your opinion.
1. NO Call of Duty is about killing primarily sure, its a huge part but winning is more important. For example, see you play CoD:Ghosts (don't! it sucks! lol) and choose ANY objective mode like "Search and Destroy" you have the bomb can choose between objective A or B so the Match starts you and your Team start running your goal is to plant the bomb sure and its your call to do your duty (pun intended) but every dead soldier on the enemy team makes it more easier to reach your destination.
Same on Turf War, painting the ground IS your objective sure, but if your teammate or yourself get one down you have this small timed window open for more turf.
And in both game modes (turf war here or search and destroy in CoD) you can have as many kills if you want if you can't succeed your goal you lose.
So tl;tr you shouldn't compare Turf War with Team Deathmatch. Because thats simply impossible.
2. The new Level Mechanic did NOT make painting less important, it only changes the favor of weapons, did you remember the times before Update 2.0? Yes? Can you remember how many people did use the Aerospray? Yes? Can you remember some people with 1300+ Points? Yes? Thats great right? Yes? No thats a huge pile of S... because most of the time they had no impact of the game, sure they had the most points but where are they when i had to deal with 2-3 enemy at once? Or where are they as i repaint the whole center? They where everywhere but they didn't help me nor the others, they only avoid combat to, you guess it, find more place to paint the ground, as we lose ground and get pushed back to our base this lovely player only paints some random places while the team can only move an inch, thats sooooooo awesome. Thanks buddy.
Besides that, you can now choose something else like a charger for example which is not as comfy to get points as the Aerospray but you get your points and with some experience maybe the same amount of money as with the Aerospray WHILE you play as team not as lone wolf, because how can you get experience with an charger if you get stuck with this "cheap" Moneymaker.
(disclaimer: won't say Aerospray is for scrubs, but the old mechanic did favor this weapon and behavior)
so tl;tr the new mechanic favors experience and teamplay rather greedy moneymaking and lone wolverie.
Overall, i really like the new mechanic because in my eyes there is now a higher diversity in most matches.
And retreating is still an important tactic something CoD isn't even worth mentioning.