Because a statement is the fundamental unit of an imperative language.

So the question "what kind of language are we trying to make?" must be answered before "what syntax would make it most legible?".

Assuming an imperative language, the simplest solution would be one command per line, no exceptions. There is a scrollbar at the bottom; or you can split a long line into more lines by using temporary variables.

No syntax can make all programs legible. A good syntax is without exceptions and without unnecessary clutter. But if the user decides to write programs horribly, nothing can stop them.

An important choice is whether you make formatting significant (Python-style) or not. Making formatting significant has an advantage that you would probably format your code anyway, so the formatting can carry some information that does not have to be written explicitly, e.g. by curly brackets. But people will complain that in some situations a possibility to use their own formatting would be better. You probably can't make everyone happy.