Why not use "native-activity"

A simple question puzzled me day after day.:frowning:
In cocos2d-x, we are using “java-jni” to support c++/c.
why don’t we use “native-activity” directly. It just looks like simple and easy.

First, cocos2d-x v2.x supports Android SDK since 2.2.
Second, native activity can not do everything as java codes could.

Thanks!