Hey Mike,
I'm glad you're interested in Dart. If you take some time to play around with it you'll see how much sense
the language, standard lib & working with packages is. It's unsurprising and you can get going in minutes.
I understand that initially it might sound counter-productive to port js libraries to Dart if all that happens is
you compile it to js again to use it in the browser. That said it actually makes a lot of sense. Usually you'll spend
a significant amount of time working in your code-base, enhancing it, changing stuff, refactoring things, …
In that day to day work having your code base in Dart yields a ton of benefits that are relevant for the day-to-day of development.
* Dart is easier to work with as a language
* The tooling (Dart analyzer) will warn you about issues that no JavaScript IDE will warn you
* Compared to js it is way easier to work with packages (Dart supports it out of the box)
* You will get exceptions if something in your code went wrong at a time when you expect it (sooner rather than later).
* No more confusion about what 'this' is and support for classes out of the box
* …
I'm obviously biased but from my POV using Dart right now (compiled to JS) already yields almost all the benefits for your day-to-day development.
Of course it would be beautiful and more pure and even faster to be able to use the Dart VM and I'm confident we'll get there eventually
but Dart as a platform is very viable today already :)
Sorry the post got so long, I didn't have the time to make it shorter. I'm sure you'll like what you see when you play