[nailer]

> We'd probably really be regretting that choice since CoffeeScript use is dwindling

BecauseJS eventually got better and everyone moved to new versions and Babel. If you'd offered an alternative, maybe they would have moved to that.

> Dart was an optionally typed language and is actually older than TypeScript.

OK.

> Is the "was" part of that intentional?

Yep, a lot of Ruby folk moved to node, now they're in Elixir or Go.

> I think you have to aim for where you think users will be, otherwise you end up irrelevant by the time you launch.

I totally agree, but I think those cowpaths give you a good idea of where the ball is moving, particularly syntactically. And it doesn't seem like Dart paid any attention to that signal at all.