Nobody uses or likes Java for its syntax. They use it for safety. Languages designed since the have gotten progressively terser. That's not preference: that's good engineering: reasonable defaults, avoiding duplicate logic, avoiding surprise, and so forth. Good design is when there's nothing left to take away.

Nobody is asking you to make everyone happy. You could have made (and still have the opportunity to make) dart look like any modern web language - coffeescript, or Python, or ruby, and you'd have both users and a measurable impact on web development.