yea it just seems like massively multiplayer games are crazy cpu intensive online, considering i do play in 1440p as well.
Unless you're seeing noticeable drops in framerate or other bugs, you really have no reason to upgrade. At all. A CPU is a 3-4 year investment
at least these days, and RAM requirements have barely increased in ten years (VRAM is another story). Ten years ago, 8GB was rather extravagant, while now it's still sufficient for the vast majority of games. 16GB is more than you need for gaming. I'd be very surprised if you managed to exceed 12GB RAM in use while gaming (unless you purposely leave Photoshop or something like that open in the background.
Save your money, put it away until you actually notice that you might have any need for an upgrade (as in: you would somehow notice the difference).
Oh, and the resolution you play at has a minimal impact on CPU usage, the GPU is pretty much all that matters there (which is why tests to demonstrate CPU differences are typically set at stupidly low resolutions and quality settings to eliminate GPU differences). The CPU load differences between 1080p and 4k are a few percent at most.