on = style
Being an old-timer, I was brought up on languages like COBOL, where programmers love to line up MOVE, COMPUTE and some other statements. I still do that when I write COBOL, as it is expected by other programmers and somehow just seems right.
But I resist the urge in Python and never do it. Previous posters have given good reasons for this. My main reason is to keep diffs as small as possible.
Small diffs would apply to COBOL too, of course. Even programmers are not always completely rational. Tradition and common practice have their say, too. (And COBOL is so verbose that perhaps it's a lost cause!)
Steve J. Martin