A good idea
What you seem to miss is that your comment completely undermines your point. Web apps *have* failed miserably in certain respect *precisely* because they are not part of the core strengths of the Web.
Your post starts acknowledging this and then rams into a wall of bad logic. It all starts with your definition of what the "Web" is. Just like Google, you seem to define "Web" as "Browser." It doesn't matter if it is portable, or consistent across platforms, or distributed, or completely open; as long as it executes within a browser it is "Web."
=> Indeed this is the whole idea: that everything should run in the browser and everything should have a certain amount of portability. If the point of project like Chrome is to remove all local apps except the browser then browser technologies need to be secure and have enough performance to perform within the browser all the tasks that are currently performed outside the browser, and currently Javascript is not up to that.