I personally find monospaced fonts a lot easier to read when dealing with code - can't put my finger on what exactly makes it that way, but it's not exclusively being able to line things up.
Funny. I always thought that too. (It's definitely not just about lining things up.)
I used to suspect it was from coding "to card" and (later on) to either a CRT terminal or a standardized input form. But there's lots of people who (mercifully) never had to deal with that nonsense that have said much the same thing.
Maybe it's some sort of gestalt or perceptual psych thing where:monospace font
= machine code and proportional font
= human language?
Interestingly enough, many editors will tell you that a lot more typos get caught when a manuscript uses a monospaced font like Courier than they do when it uses a proportional font like Times.
Apparently there's something going on that your brain mentally
fills in, glosses over, or corrects more when it's reading proportional fonts.