You can read their blog about the AI-crap, in terms of their approach and philosophy. In general, it is optional and not part of the major experience.
The main reason I use kagi is immediately obvious from doing seaches. I convinced my wife to switch to it when she ask, “ok but what results does it show when I search sailor moon?” and she saw the first page (fan sites, official merch, fun shit she had forgotten about for years).
What you need to know is that you pay money, and they have to give you results that you like. It’s a whole different world.
Also meta but while I am big on slamming AI enshitification, I am still bullish on using machine learning tools to actually make products better. There are examples of this. Notice how artists react enthusiastically to the AI features of Procreate Dreams (workflow primarily built around human hand assisted by AI tools, ala what photoshop used to be) vs Midjourney (a slap in the face).
The future will involve more AI products. It’s worthy to be skeptical. It’s also worthy to vote with your money to send the signal: there is an alternative to enshitification.