avoiding a new layer of abstraction because it can just about be done in vanilla rails isn't a solution, it's just throwing more lines of code at the problem.
recently i've found that everything i do at the frontend intermixed with the controller, models and helpers could be made simpler with two way databinding.
it's also simpler, if someone want's to see if it looks right you can plug in some fixtures and tweaking css can be done independantly instead of needing to write something in ruby to affect how something in html looks.
maybe for a project with a large codebase is to use lighter frameworks such as backbone rather than having to do full rewrites in emberjs or angularjs. and let the code rewrite itself, ie. just clean up the portions of code that were only there for presentation.