Something I have found strange since I started working on GWT is how few open source projects there are in this technology.
Initially I was surprised to discover this mainly because GWT itself is open source. But after puzzling over this, my suspicion is that it is mainly used for internal projects by large corporations who already use Java and are using GWT for their RIAs instead of Flex or Rails. My understanding is that large corporations that use Java would tend to have lower contributions to open source because their focus is mainly on internal or commercial applications.
Does this sound like an accurate interpretation or does anyone have a different explanation for this phenomenon?
It actually seems quite reasonable to me that corporations, particularly those who use closed source, would favor GWT more than open-source developers, for exactly the reasons related to those mentioned in the question:
Open-source developers, on the other hand, are often hobbyists (though not always), and hobbyists tend to be more interested in picking up new technologies “for the fun of it.” Thus a hobbyist would be more open to writing Javascript directly, probably with the aid of a Javascript framework that doesn’t involve translating from some other source language.
Specifically concerning source language translation, it’s a leaky abstraction. Eventually you’re probably going to want to drop down into “raw” Javascript, and it’s easier to do in an environment where you’re already writing JS than one in which you’re writing Java that gets translated.