All the eco templates are compiled and shipped along with the JS files. The server backend only sends JSON to the app. Its much smaller and faster to render, plus its cacheable on the client side. Its a huge win over RJS templates.
It seems to me that you could do something similar to how ActiveRecord queries the database for a model's attributes - but instead expose a JSON service that returns a models attributes and validations. But perhaps JS doesn't have the dynamic / meta-programming capabilities to make this happen like Ruby does.