It's a simple answer. Dev's make more demanding games as GPU's get faster. They do so, so that people on 1080p and 1440p have a reason for high end hardware. 4K will always require more power than 1080p and 1440p.
The question you have to ask yourself is, "is 4K at lower visual settings better looking to you, than 1440p or 1080p at higher settings?" The only reason 4K can handle max settings is if dev's decide to hide higher quality settings from you, and make 1440p and 1080p capable of being run at max on low end hardware.
For some odd reason, many people like yourself, don't consider anything but Ultra acceptable, despite the fact that Ultra is likely no where near the highest settings the game could show should the dev's show you all the settings. As someone above mentioned, 4K at 60 FPS is very achievable on a wide range of hardware. Just pick settings that your hardware can handle.