This is evidence that S-expressions are objectively superior to other serializations. They are objectively simpler (this is why they were chosen in the first place -- writing a parser for sexprs is vastly easier than writing a parser for just about anything else), and the fact that humans who become accustomed to them early on generally prefer not to move away from them is evidence that other representations offer no advantages, and considerable disadvantages in the form of added complexity for no objective benefit. In other words, the main reason people don't like S-expressions is that they are indoctrinated from an early age (like grade school) into objectively inferior serializations, which trace their roots literally into antiquity.
Lisp should be taught in elementary school. Children should be taught to think not in terms of of "two times three" and "two plus three" but rather "the sum of two and three" and "the product of two and three". It would make the world a better place in the long run.