This can be done without the radical switch to modeling everything client-side. I mainly do java web apps with JSP's (which everyone seems to think is stodgy and past its prime) but its rather simple to do something like what you're describing with keeping things up-to-date. I simply have broken my project down into "widgets" that self-load so a page actually is made up of many widgets that use javascript to call various server-side controllers, you can then set them to do whatever you want (such as refresh every 30 seconds) and it doesn't require some massive client-side data model.
I agree, there are cases where you would want a more robust client side data model, but, IMO people are a bit too quick to jump to using this and it can make more work in the end and make a project more costly to maintain. I think the cases where it is useful are mainly for highly interactive sites like those that would have previously done in flash, with animations (such as games, etc), for just regular CRUD webapps I feel its a bit of overkill
