Because I have seen many GWT apps and I never saw GWT being used that way, I can't see how a very large portion of developers completely misunderstood the right way of using a framework.
Usually the full GWT ecosystem is used in order to build enterprise apps: templates in UIBinder, GWT widget hierarchy, MVP frequently not always, Editor often, Request Factory often, etc.
You mention that the problem is compilation times, but this is not a problem. In Dev mode there is no need for compilation, the compilation happens in the background in the build server whenever a release is needed.
What you describe for GWT 3 seems way more complex that just using plain Html, CSS and Javascript with some framework on top.
I don't see how all that complexity of compilers and plugins and dev modes can pull it's weight compared to one 100k js file.