Yes, familiarity influences preference, and infix is familiar. Almost all adults who develop software have had 12 to 20 years of practice using infix notation

Yes, familiarity influences preference, and infix is familiar. Almost all adults who develop software have had 12 to 20 years of practice using infix notation as a standard part of mathematics, and it's also a standard part of practically all programming languages except Lisp and Forth. It's possible to notate calculations without infix (obviously!), but that doesn't mean that people WANT to do it. It's absurd to fight against the worldwide standard of infix notation for standard math operations like "+". For most people, {2 * {3 + 4}} is easier to understand than (* 2 (+ 3 4)). If a Lisp reader simply treats {...} as a list, where the operator is the even positions, then you have the best of both worlds: standard infix notation combined with Lisp's ability to do quasiquoting, macros, etc.