To me, having consistent indentation does make a substantial difference - it is fundamental to understand at a glance what structures are present in the code, rather than "parsing" it in detail every time I'm looking for something.

Consistency is the main point. The second layout is more compact and this makes a huge difference if you need to put code in a document (also a small difference for websites).

Having more compact code allows to have more code on the screen without using the scrollbar. For me, it is also more readable because I am used to it.

If I saw this in a codebase, I'd assume the programmer's fingers slipped a lot.