In those discussion, Bruce from Google told us that GWT’s motivation is “to be as small and as efficient as possible” and its two separate goals are:
(1) Create highly optimized JS output
(2) Optionally, publish selected parts of your code with a JS-compatible API
I thought that wais a very clever design. And I admired GWT team for its “excellent 100k ~ 200k final *.js files with very good performance”.