For me it was the part about typing JSON. I work at a company with a Common Lisp back-end and Let Me Tell You. Trying to enforce the JSON structure it generates using any kind of front-end JS types, so that nil-punning doesn't crash the UI every other day, is an exercise in attrition. Unfortunately JS is not Clojure and so can't as elegantly digest inconsistent data, but I certainly have learned to appreciate the appeal of that philosophy.