One of the really nice things about Backbone is you can you as little or as much as you need. Don't need collections? Don't use them. No need for a controller structure? Not a problem. You could also build your own thinner structures on top of its Event structure to get the advantages of event-driven callback structures without any of the other stuff.

It sounds to me like you're using controllers because it seems logical coming from a Rails background, not because you need to. Take a look at the example Todo app - no controller, entirely atomic screen repaints as needed via collection/model to view bindings.

The models provide a framework for things like validation or presenter methods and keeping data and methods separate as well as a framework for event binding with a really, really nice syntax.