What do the motivating factors behind Clojure have to do with anything?

Motivating factors dictate current practices. If every piece of Clojure PR says things like "harness all the power of Java from a language that uses Lisp semantics/syntax", of course library authors will be comfortable doing so.

Part of the reason Clojure is great is because we don't have to re-implement all the functionality that Java libraries have given us in order to have a viable language. That benefit goes away if we start saying "stay away from Java".