Such an approach would have many advantages; for example, we would no longer require a plethora of ad hoc mechanisms, such as .xsession, .Xrdb, .login, .cshrc, and autoexec.bat to recreate some of the state of the user's environment, since all of the dynamic state would be captured in the snapshot.
Startup files, such as .cshrc, are no longer needed, since the environment they attempt to recreate is persistent.