Fashions change. Now it is cool to do things client-side: AJAX, etc. mean that client-side is now considered a "good thing" - actually this could be good for quality HCI in browser-based application, sadly it rarely is as the developers all too often have no idea about HCI and what makes a good user interface.
Now there are rumours that people who like Mono are saying that CLI should be included in all browsers. Apart from all the software patent issues because Microsoft own patents in CLI, is this just Mono folk being shills for Microsoft trying to get .NET as the standard for all Internet-based activity?
History tells us that the JVM (of which CLI is a rip-off) can already be used client-side in browsers, so why not just return to using Java applets? Computers are now vastly more powerful than they were when applets stopped being all the rage. Perhaps if they were tried again, they could become all the rage again.