If the syntax is not important, that would mean coding in whitespace or malboge would be as easy as coding in python
The GP is factually wrong. There's plenty of empirical evidence to indicate that language influences thought, and that syntax is therefore important.
Although, I would point out that while your argument ad absurdum is generally reasonable (the fact that syntax can make the difference between a very good language and an unusable one), whitespace and malbolge also have terrible semantics that contribute to them being unusable.
As a former Lisp enthusiast (and still an enjoyer), I'd actually use my own darling as an example: Lisps have amazing semantics and are generally good languages. Their syntax is highly regular and structured and easy to parse...except that it's brain-hostile, and I'm convinced that it actively makes it harder to read and write - not just adopt, but actually use.
Rather, the sort of beauty it's going for here is exactly the type of beauty that requires a bit of abstraction to appreciate: it's not that the concrete syntax is visually beautiful per se so much as that it's elegantly exposing the abstract syntax, which is inherently more regular and unambiguous than the concrete syntax. It's the same reason S-exprs won over M-exprs: consistently good often wins over special-case great because the latter imposes the mental burden of trying to fit into the special case, while the former allows you to forget that the problem ever existed. To see a language do the opposite of this, look at C++: the syntax has been designed with many, many special cases that make specific constructs nicer to write, but the cost of that is that now you have to remember all of them (and account for all of them, if templating — hence the ‘new’ uniform initialization syntax[1]).
[1]: https://xkcd.com/927/
This trade-off happens all the time in language design: you're looking for language that makes all the special cases nice _as a consequence of_ the general case, because _just_ being simple and consistent leads you to the Turing tarpit: you simplify the language by pushing all the complexity onto the programmer.
Visually-heterogeneous syntaxes, for all of their flaws, are easier to read because it's easier for the human brain to pattern-match on distinct features than indistinct ones.