Coming from Rails, I tend to agree that the Clojure ecosystem is still less mature, but not by as much as I initially thought.
Missing Rails I18n, SimpleForm, or validations? Clojure has you covered:
* https://github.com/ptaoussanis/tower
* https://github.com/asmala/clj-simple-form
* http://clojurevalidations.info/
Need more specialized libraries? Take a look at ClojureWerkz:
Having tried hard to understand the rather labyrinthine source of the original SimpleForm library, I was astonished by how easy Clojure made writing a similar library, clj-simple-form. The key contributing factors were Clojure's emphasis on simple data structures and powerful functions as opposed to classes, and the ability to pass around functions just like any other objects. For a lot of projects, I find ease of extensibility to be more important than ready libraries.