Using monospaced when not necessary feels weird, because everything is unnaturally spaced too wide. Some do like the "typewriter" vibe, but in my experience most do not, and that's why fonts have variable spacing.

That's also why most monospaced fonts (and typewriters) tended to make letters such as 'i' or 'l' larger, not only for clarity, but also to fill up the ugly blank space around them. That's also important due to the fact that a blank space has it's own semantical meaning.