I understand your perspective, but I argue that there is a difference between adding a new feature that is unique to your language (I think we would both agree that Scala does not need any more of these), and adding a feature that makes the language more consistent with the syntax that most people coming from other languages expect to be there.
I teach Scala at a university level, so I very much do care about learners and beginners. In my opinion, having a syntax for collection literals would make the language a little more approachable, as my students are coming from languages that do provide this syntax (e.g., Python).
I see what you're saying, but isn't familiarity worth something? After all, Brainfuck is incredibly simple and consistent :)