[matthewmacleod]

That's just not the whole story. Significant whitespace can itself cause issues - for example, it can be really easy to accidentally indent to the wrong depth when merging or copying and pasting Python code.

Ultimately, well-formed indentation and whitespace is important, as you say. But whitespace significance is not a panacea.

[marcosdumay]

Well, personally I don't like whitespace significance... But then, I wonder if forbidding spaces* at the beginning of the lines wouldn't correct all the problems.

* Yes, mandatory tabs. I know lots and lots of people will disagree, those lots and lots of people are wrong. Spaces are ambiguous, and have different semantics on different context. In a flexible language that does not make much difference, but when you want whitespace to have a specific meaning, it does.