Clojure doesn't have much manpower, being a niche language and all, so maybe that's where your impression comes from. It's hardly on purpose, and there's many examples of software that ships with another language as public API.
Rama is written in clojure but the main api is java
Klipse is written in cljs but is marketed as a "javascript library"
Rama[1] for example launched with Java API first. Probably for some reason Datomic just didn't get traction with JS users for some nontechnical reason.
Clojure doesn't have much manpower, being a niche language and all, so maybe that's where your impression comes from. It's hardly on purpose, and there's many examples of software that ships with another language as public API.
Rama is written in clojure but the main api is java
Klipse is written in cljs but is marketed as a "javascript library"
Even Datomic maintains a java api