Perhaps they still haven't solved the SEO problem of GWT internally, and so only things that don't need SEO-features like control panels, dashboards (but ironically, the google groups forums too) are in GWT.
I don't think the SEO nature of GWT is fundamentally different from Closure or Angular.
http://www.google.com/fonts <-- loads fast for me. In fact, i think GWT apps can do loading in such an optimized way that hand coding js will only beat it if the programmer is very very careful about it.
(ps, i have no affiliation with google, i just don't like mistunderstood tech to suffer…)
I used GWT for a while and it would be great for enterprise and large teams. The static typing which I usually love/insist on though, does seem pretty cumbersome for something as simple as a web page. I've switched to scala play for the back end and lots of tiny angular 'apps' on the front, and it's so much faster to develop for.