If you always implemented it the most general way, sure, but most people don't write lazy, curried functions when using JS (and often needn't when writing Haskell even though it makes more sense in that case).
As always, its a matter of preference. Fay is for devs who prefer the syntax and semantics of Haskell before that of JS, and it will not solve anything else beyond that. The overhead is likely neglible in most cases, and is probably worth it if it lowers development time.
