When a .cljc file that contains macros is required and aliased in another namespace, macros are not automatically included. In that case the :include-macros flag must be set to true. Since the .cljc file is experienced as a single file one would expect macros to be included just like in Clojure.
The reason we don't do it automatically already is because it wasn't safe to do so when macro files and runtime files were separate
in the past just because a .clj file and .cljs file had the same name didn't mean anything all - implicitly loading the .clj file was not a good idea.