This is an interesting observation, not really something I have considered. The key difference here is that you are the one in control of those customizations. Whether the customizations are useful or harmful is entirely up to the user, Kagi just gives you the option.
For me at least, the majority of my searches I just want the correct answer to a question or a link to a specific resource I’m looking for. I don’t really use it as a content discovery engine. Being able to prioritize sites that I have found through experience to have reliable results and exclude sites that are uninformative or irritating is valuable.
Do note though that for privacy purposes, a .us domain is not the best idea. You must be a U.S. citizen or business and registrars may try to verify your identity.