Reason for Android onscreen keyboard not disappearing on outside touch event

Some UX expert at my job noted that the Android onscreen keyboard should disappear once the user taps any UI component but the focused EditText (or the keyboard itself of course). Apparently Stackoverflow has multiple people asking for technical solutions to this behavior (e.g.: http://stackoverflow.com/questions/4165414/how-to-hide-soft-keyboard-on-android-after-clicking-outside-edittext). Of course it's always possible to collapse the keyboard via the system back button.

So I was wondering whether this was by design and workarounds should not be applied at all, or this can even be considered some kind of bug?