Hm, I have the exact opposite interpretation. This is exactly the kind of feature that leads to arguments. If `unless` didn't exist, what argument could people be having about using `if !`?
In a shared codebase, I think there should be as few (equally effective) ways to express an idea as possible. (Obviously there can be more- and less-efficient ways to write a function; I'm referring only to style.) The more arbitrary choices people have, the more time is wasted on choosing one.
If you're coding alone, that's fine - you just pick what you like, and spend as long as you like making that decision. But in a shared codebase, developers writing in different styles is a net negative on quality & readability. Spending time debating which style to prefer is a worthwhile, but unnecessary time sink. Automatically enforcing a pre-defined style is efficient and effective - that's why Prettier exists, is widely used, and has few configuration options.