GWT was amazing at the start, I loved it, and I agree with all your points, some of these are things JS frameworks are just starting to reinvent.

But then the project got big and it was the worst coding experience.

The compile phase was taking way too long (5m), to the point that we had to buy SSDs for everyone, this was back in 2010.

And integrating 3rd party JS was bad, just like JNI. We were missing so much of what was offered with open source JS.