There've been so many attempts, of various stated motivations. Many of them have been expressly to make it more familiar to programmers (not mathematicians). Which, for all of the time I've been in Lisps, has meant the series of languages that mimicked the syntax of the language before, for the same familiarity/acceptance reason: C, then C++, then Java, then JavaScript. There's also been the indentation-sensitive ones that are influenced by Python. And the math ones.