Practically, we look at text all day long, so having a font that is easy to read is good ergonomics. A font may be good for code, but might not work as well in a tool like htop or gotop.

Monospaced fonts are also interesting from an artistic perspective that resonates with programmers. Font designers are able to be expressive and original despite — or perhaps because of — the constraints of the problem: all characters must have the same width and the text should be readable for long periods of time, often at small sizes.