Rails should stop messing with Javascript all together. Drop JQuery, CoffeeScript, TurboLinks and what not and let the users decide what to use, make it optional. Rails shouldn't require a JS engine in order to run.
You're missing the central point of default rails stack. http://david.heinemeierhansson.com/2012/rails-is-omakase.htm...
Most sites require jQuery, most developers are happy using it, why put the effort into getting rid of it?