Why Lisp?
The reason that Lisp is so cool and powerful is that the intuition that leads people to try to represent code as data is actually correct. It is an incredibly powerful lever. Among other things, it makes writing interpreters and compilers really easy, and so inventing new languages and writing interpreters and compilers for them becomes as much a part of day-to-day Lisp programming as writing parsers is business as usual in the C world. But to make it work you must start with the right syntax for representing code and data, which means you must start with a minimal syntax for representing code and data, because anything else will drown you in a sea of commas, quotes and angle brackets.
Which means you have to start with S-expressions, because they are the minimal syntax for representing hierarchical data. Think about it: to represent hierarchical data you need two syntactic elements: a token separator and a block delimiter. In S expressions, whitespace is the token separator and parens are the block delimiters. That's it. You can't get more minimal than that.
