They are only used in case-of and monadic blocks, and allow avoiding commas and semicolons everywhere else without having the annoying issues with meaningful spaces! I totally understand your initial impression, but consider reading my thoughts below before judging prematurely. (Guess I'll end up adding a bracket-less version of case-of to satisfy the hyper demanding crowd of HackerNews...)
Nooo don't compromise your vision for hacker news commenters!
Great product design is a mix of flexibility and opinionatedness. You have to find your "users" and then build the thing they want. If HN commenters give you crap about it they're not your users, at least not yet, and that's ok. Your product doesn't have to appeal to everyone at the outset.
