The benefit to Google of the current mode is the ability to rapidly change the code pushed to your browser. If there was a open source release of the gmail cli

The benefit to Google of the current mode is the ability to rapidly change the code pushed to your browser. If there was a open source release of the gmail client code, it would force google into maintaining an API for that code for the foreseeable future, which would require additional effort. The closest to this request that seems remotely likely is a client side API for gmail, so that browser plugins or third party services could extend it. I see a lot of cost to Google to actually release the code, and not a ton of benefit.