It makes sense if the web is going to be divided up between "documents" and "applications" (which it is, whether anyone likes it or not) not to run the applications in an environment designed to display documents.
Bonus points if the default is to download, cache and update the source code and "installation" is just local compilation to an appdata folder or something, similar to what browsers do with HTML, CSS and JS, rather than just download a blob of bytecode. That would make the FOSS people happy.